By: Edward T. F. Wei PhD
Colonic transit studies are important for cases of chronic megacolon due to prostate oncology center purchase casodex uk colonic inertia prostate cancer stage 7 generic 50mg casodex free shipping. Hypoalbumine mia is due to mens health aus discount casodex 50mg mastercard protein loss and decreased hepatic synthesis due to prostate 1 cheap casodex 50 mg amex chronic infiammation and malnutrition man health 3rd discount casodex on line. Biopsies of the rectal and colonic wall demonstrate the absence of ganglia provide a definitive diagnosis. Ifthepatient is to xic or has peripheral leukocy to sis, s to ol specimens should be sent for culture, microscopic analysis, and C. General Measures Repositioning of the patient results in redistribution of air in the colon. Exclude mechanical obstruction (with a hypaque enema or sigmoidoscopy), discontinue medications that would adverselyaffectcolonicmotilityandcorrectmetabolicdisturbances. Theini tial therapy is medical, which is successful in preventing surgery in up to 50 percent of patients. Megacolon 963 Treatment Options Endoscopic decompression should be performed in patients who do not respond to neostigmine or relapse. Surgical resection and colos to my are indicated if ischemic bowel or perforation are sus pected. Repeated rectal irrigation with saline decompresses the colon and may decrease the severity of disease. Surgical excision of the agan glionic segment and a decompressing colos to my should be per formed as soon as the child is stable and the diagnosis established. Side Effects and Complications Neostigmine causes bradycardia, colic, hypersalivation and nausea. Routine In chronic megacolon, colonic evacuation with osmotic laxatives and enemas may suffice. A sub to tal colec to my with ileorectal anas to mosis or a decopressive ileos to my may be needed. The diagnosis can be confirmed with a con trast enema, which may also de to rse the volvulus. Surgery is indi cated if de to rsion is unsuccessful or if bowel necrosis or perforation is suspected. Signs & Symp to ms Flesh-colored or slight pink globose papules with a central dell Lesions may be single or may coalesce. Treatment Options Usually mucormycosis is refrac to ry to medical treatment, necessi tating larger doses of Amphotericin B. Myelodysplastic Syndrome 1029 Dyserythropoiesis: multinuclear forms, nuclear fragments, mega loblastic changes, nuclear:cy to plasmic dyssynchrony, ringed sider oblasts on iron stain Dysthrombopoiesis: bizarre nuclear forms, decreased ploidy, “pawn ball” nuclei, micromegakaryocytes Increased myeloblasts Other Tests: Cy to genetics on bone marrow; characteristic abnormalities = dele tions. Transfu sion guidelines: platelets <10,000/mcl, clinically significant bleed ing, surgical procedure. Myelodysplastic Syndrome 1031 Treatment Options 5-Azacytidine (Vidaza, Pharmion, Inc. Response rate was karyotype-dependent and highest in patients with chromoso mal deletions of 5q31. Attentive moni to ring and patient education for signs and symp to ms of infection, especially in neutropenic patients. Narcolepsy 1041 tests Diagnosis made clinically Routine blood studies are normal. Signs and Symp to ms Junctional nevus = fiat lesion, characterized by pigmentation w/ sharp margin; usually symmetrical & small Intradermal nevus = elevated, sharply demarcated lesion, usually nonpigmented Compound nevus = combination of features of junctional & intra dermal nevi; elevated, sharply marginated pigmented mole Atypical mole = has one or more characteristics of melanoma (see below) fi Clinically suspicious lesions, suggestive of melanoma: r Morphology (A, B, C, Ds): r Asymmetry r Border irregularity r Color – variation w/in lesion r Diameter >6 mm r Pruritus or other sx r Recent accelerated growth pattern r Changes in “mole” such as growth, bleeding, irritation tests Labora to ry Excisional biopsy of suspicious lesions for derma to pathology exam ination His to logic evaluation of margins Clinical Dermoscopy (epiluminesence microscopy): reserved for experts in this technique Pho to graphy of all areas w/ nevi can be used to evaluate presence of new lesions or changes to existing lesions. Signs & Symp to ms Pulmonary infection presents as cough, fever, weight loss, malaise and can be insidious or acute. Usually faster-growing, more common on dorsum of hands, involve vermillion surface of lower lip. Nevus: Softer,non-ulcerated,nobleedingortelangiectasiaandlongerdura tion Sebaceous hyperplasia Yellowish nodules with depressed center. Scar or morpheaform: Usually no bleeding, crusting or progression of size Seborrheic kera to sis Waxy, brown with “stuck-on” appearance Malignant melanoma May be indistinguishable from pigmented variety. General Measures Oral antifungal agents required Debridement of dystrophic nail Topicalagentsareavailableandmightbeusedasadjunctivetherapy. Signs & Symp to ms Tenderswellingoftheposterioraspec to fthescrotumwitherythema is found early. Imaging If symp to ms do not improve within 3 days of antibiotic therapy or if complications occur during the course of epididymitis, do ultra sound. Orchitis and Epididymitis 1091 Testicular infarction or tumors such as lymphoma can cause swelling. Side Effects & Contraindications Ceftriaxone fi Side effects: rare allergic reactions fi Contraindications: r absolute: penicillin hypersensitivity. Aortic and mitral insufficiency very infrequent tests Imaging Wormian bone (unmineralized cranial occipi to -pareital islands) in 60% of infants or young children. Osteogenesis Imperfecta Osteomalacia and Rickets 1099 Bisphosphonate therapy, oral (alendronate, residronate) or intra venous(pamidronate;zoledronicacidnotreported):decreasesfrac ture rate, increases bone density in children. In adults may increase bone density transiently, but effect on fracture rate not defined. Vitamin D inadequacy very common, must be corrected before any treatment for osteoporosis can be effective. Presence of a single compression fracture increases subsequent fracture risk 5-fold. Diseases should include: choledocholithiasis cholangiocarcinoma Pancreatic Cancer 1127 bile duct strictures sclerosing cholangitis management What to Do First Initialassessmentisdirected to wardwhetherthelesionisresectable. Symp to ms and Signs Because of improved imaging techniques, pancreatic cysts are often incidentally found. There is currently no definitive approach aside from surgical resec tion to determinewhetheracystrepresentsaneoplasticlesion. Mos to ften,thegoalis to differ entiate mucinous cystic tumors from serous cystadenomas. Differ entiationbetweendifferentcysttypesisoftendifficult to distinguish from each other prior to resection. Surgical outcomes of pancreatic resec tions are much better in institutions where the volume is high and the necessary expertise is present. General Measures Antibiotics for bacterial infection, cleansing baths, wet dressings, pain management specific therapy Mild/localized disease can be treated with to pical and intralesional corticosteroids along with dapsone or a tetracycline. Manual compression using the hand or a pediatric blood pressure cuff around the penile shaft to squeeze out edema also a useful technique. Manual traction may result in successful replacement of the foreskin to normal position. Relatives with similar attacks of pain or a devastating, undiagnosed neurological condition. Signs & Symp to ms Tachycardia common; fever usually absent On abdominal exam, reduced bowel sounds (suggestive of ileus); diffuseorfocaltendernessbutlessthandegreeofpainwouldsuggest. Values in 2–20 mg/24 h range may identify a “silent” genetic carrier of the disease. Panhematin is sup plied as powder, which is reconstituted immediately prior to infu sion. Recovery from mo to r neuropathy is slow (many months) but in many cases is complete. Prior pregnancy his to ry Prior seizure disorder Hypertension, thromboembolic events, liver disease, renal disease, surgical his to ry (esp. Signs & Symp to ms Ulcerationoverthesacrum,coccygeal,ischialtuberositiesorgreater trochanter Begins as an erythema to us, induration Ulcer may be very deep. It is typically much more severe and presents earlier in life than the dominant form. Pyogenic Granuloma Pyogenic Liver Abscess 1257 follow-up After removal, no follow-up is usually needed. Includes hyperopia (farsightedness), myopia (nearsightedness), regular astigmatism, and presbyopia (age related loss of accommodation). Pathologic myopia is uncommon, characterized by progressive myopia with scleral and retinal thinning that can cause permanent visual loss. Rigid gas-permeable contact lenses can be used to correct both regular astigmatism and irregular corneal astigmatism. Presbyopia Prevalence – Presbyopia is a universal, progressive, age-related loss ofaccommodativepower,withsymp to maticonsettypicallybetween ages 42–46. Onset occurs earlier in hyperopes since a portion of the accommodative reserve must be used to correct the hyperopia. Subjective refraction is the process of determining the underlying refractive error by presenting lenses of varying powers until the patient reports that a small target image is in sharpest focus. Objective refraction is the process of measuring the underlying refractive error using retinoscopy (manual or au to mated) or aberrom etry. Objective refraction is invaluable in measuring ametropias in chil dren and in uncooperative patients. Clear lens extraction in the absence of cataract is gen erally avoided as a means of correcting high myopia because of the elevated risk of pos to perative retinal detachment in these patients. Regression of effect is a frequent occurrence with this method, particularly with correction of higher degrees of hyperopia. Lens procedures that increase the net effective convex power of the crystalline lens: Phakic intraocular lens implantation – an artificial lens is placed in the anterior or posterior chambers, but the natural crystalline lens is left intact Clear lens extraction with intraocular lens implantation – the undoubtedeffectivenessofthismethodofcorrectinghigherdegrees of hyperopia must be balanced against the uncommon but poten tially serious complications of an intraocular surgical procedure. However, the risk of pos to perative retinal detachments is lower in lens extraction performed in hyperopes than in myopes. Irregular astigmatism requires correction with a rigid contact lens that can “fioat” over the tear film, thus neutralizing the underlying irregular cornea. Irregular astigmatism is more difficult to correct and may require special techniques such as “cus to m corneal ablation,” in which a small or variable-diameter beam excimer laserisdirectedina to pographicallyorwavefront-guidedfashion to “smooth” the irregular corneal surface. This convex power is “added” to any underlying lens power used to correct a co-existing ametropia, either in the form of bifocals or reading spectacles. Specially designed bifocal contact lenses can also be used to correct pres byopia. Monovisionisamethodofcorrectingoneeyefordistance and the other eye for reading, thereby sacrificing depth percep tion and stereopsis. Alternatively, a kera to refractive or lens-based pro cedure may be used to create a monovision correction. Unilateral renal artery disease often responds to blockade of renin angiotensin sys tem. Proven long-term durability and patency in most cases, but higher early morbidity and surgical risk than endovascular techni ques. Renalfunc tion may improve in patients with pre-existing renal dysfunction (25–30%), remain unchanged 45–50%) and deteriorate in 20%. Often first consideration when abnormal pulmonary ventila tion/perfusion scan noted. Doppler ultrasound may identify lack of fiow within renal vein but is opera to r depen dent. Tumor resection in this case requires attention to avoid thrombus fracture and embolic phenomena. Rhegma to genous Retinal Detachment 1297 tests B scan ultrasound – performed when poor view of retina – shows elevated retina.
Self-awareness: Sense of knowing oneself prostate function buy cheap casodex 50 mg on-line, particularly in terms of insight in to prostate yew buy 50mg casodex overnight delivery one’s own psychodynamics prostate cancer janssen cheap casodex 50mg line. Self concept: the sum to mens health 7 tests of true strength buy casodex 50 mg overnight delivery tal of the ways in which the individual sees her or himself mens health nutrition guide 2013 discount casodex online amex. Self-concept is often considered to have two major dimensions: a descriptive component, known as the self-image, and an evaluative component, known as self esteem, although in practice the term is more commonly used to refer to the evaluative side of self-perception. Self-consciousness: An exaggerated awareness of one’s own behaviour, feelings and appearance, 370 Dictionary of Psychology & Allied Sciences combined with a belief that other people are equally aware, interested, and critical. Self-disclosure: the process through which one person lets himself or herself be known by another. Self-discovery: In psychoanalysis, the freeing of the repressed ego in a person who has been brought up to submit to the wishes of the significant others around him. Self-esteem: the personal evaluation which an individual makes of her or himself; their sense of their own worth, or capabilities. Excessively low self-esteem is regarded as indicating a likelihood of psychological disturbance, and is particularly characteristic of depression. There are several simple questionnaires which have been developed for measuring self-esteem, as well as more sophisti cated tests such as the Q-sort. Self-fulfilling prophecy: A dis to rtion of a event or situation that eventually leads an individual to behave as he is expected to behave by others in his social setting. The classic example of the self fulfilling prophecy in action came from work by Rosenthal, in which undergraduate students were given a set of experimental rats to train in maze running. Despite the fact that there were no observable behavioural differences between the rats at the start of the experiment, the students were to ld that they could expect some to be very quick at learning the maze, while others would be very slow. The rats performed according to these predictions, because the predictions had induced expectations on the part of the students which affected how they handles the animals during training. Further studies by Rosenthal and his colleagues demonstrated the power of expecta tions held by teachers to wards their pupils, and the self-fulfilling prophecy is now considered to be a major social influence which needs careful control in psychological investigations. Dictionary of Psychology & Allied Sciences 371 Self-image: A person’s conception of his own identity, personality and worth as a person. Self-perception theory: the idea that we gain know ledge about ourselves by observing our own behaviour. Overtly such an approach may appear native, yet there is considerable evi dence to suggest that people do make attributions about their own behaviour based on how they have seen themselves acting or reacting. Self-persuasion: the modifications of a person’s beliefs to become consistent with what they observe about their own behaviour. Self-realization: Psychodrama technique in which the protagonist enacts, with the aid of a few auxiliary egos, the plan of his life, no matter how remote it may be from his present situation. For instance, an accountant who has been taking singing lessons, hoping to try out for a musical comedy part in summer s to ck and planning to make the theater his life’s work, can explore the effects of success in that venture and of possible failure and return to his old livelihood. Self-reference: Term denoting a person’s repeatedly referring the subject under discussion back to himself. Self-schema: A cognitive generalization about the self, derived from past experience that organizers and guides the processing of self-related information contained in the invidual’s social experiences. Self-system: Sullivan’s term for a personalty system designed to ward off anxiety and preserve a positive view of the self. Semantic: To do with meaning, the intended communi cation or meaning which underlies any utterance or signal. The word semantic usually used in contrast with syntactic, referring to the structure 372 Dictionary of Psychology & Allied Sciences of the communication. Such contrasts are particularly useful in examining the use of language in communication. Semantic conditioning: A conditioning process which uses a stimulus-response form of learning like operant or classical conditioning, in which the individual is trained to respond to the meaning of a word or phrase. Although the perception of meaning is a cognitive rather than a behavioural event, studies of semantic conditioning are report to show all the characteristics of behavioural condi tioning, such as generalization, discrimination, etc. However, there is a certain amount of evidence to indicate that semantic conditioning only ‘works’ if the subjects catch on to what the study is about, and decide to cooperate. Semantic differential: A method of measuring the connotative meaning of words and concepts. Semantic memory: A long-term memory s to re contain ing the meanings of words, and concepts and the rules for using them in language. Semantic relations grammar: A theoretical approach to understanding the way in which very small children put word to gether, which emphasizes the meaning, or intention, underlying the utterance. The short sentences and limited utterances of the child are viewed as telegraphic speech, signalling the most important parts of the communications, and only becoming more refined in terms of additional words or word endings later on. The theory was developed by Roger Brown in opposi tion to the view of language acquisition developed by Chomsky, which largely ignored what the child was intending to communicate and concentrated instead on the structure of the utterance. Semiotics: the study of pattern in communication of all kings, including language, ritual, non-verbal Dictionary of Psychology & Allied Sciences 373 communication, animal communication, etc. Although primarily concerned with the meanings within such communication, the study of semeio tics also sees the form of the communication as providing important clues to that meaning. In other words, a clear distinction between meaning and form is not considered appropriate, as the form will influence the meaning, and the intended meaning will affect the choice of the form. For example, a reminder to staff in an office from the boss about switching off unnecessary lights could be deli vered as a spoken communication, a hand-written memo, or a formally typed memo. Although the words might be identical, the form affects the meaning of the communication. Senile dementia: Dementia secondary to diffuse cerebral atrophy associated with advancing age. Senzation: Feeling or impression when the sensory nerve endings of any of the six senses – taste, to uch, smell, sight, kinesthesia, and sound – are stimulated. Sense of self: A person’s feeling of individuality, uniqueness, and self direction. Sensitive period: A time period during development in which a given capacity or form of learning can be acquired more easily. Sensitive periods are distinguished from critical periods by the fact that the capacity can be acquired outside the set period, though with greater effort. Sensitivity training group: Group in which members seek to develop self-awareness and an under standing of group processes, rather than to gain relief from an emotional disturbance. The first step in achieving this, according to Piaget, is the reduction of the infant’s egocentricity to the point where it can distinguish between ‘me’ and ‘not-me’, and has formed its first schema, the body-schema. Another important miles to ne during this period is the development of object constancy. See also pre operational stage, concrete operational stage, formal operational stage. Sensorium: Hypothetical sensory center in the brain that is involved with a person’s clarity of aware ness about himself and his surroundings, including the ability to perceive and process ongoing events in light of past experience, future options and current circumstances. Sensory deprivation: Lack of external stimuli and the opportunity for the usual perceptions. Sensory deprivation may be produced experimentally or may occur in real-life contexts – for example, deep-sea diving, solitary confinement, loss of hearing or eyesight – and may lead to hallucinations, panic, delusions and disorganized thinking. Sensory extinction: Neurological sign operationally defined as failure to report one of two simul taneously presented sensory stimuli, despite the fact that either stimulus alone is correctly reported. Sentiment: A configuration of emotional dispositions oriented about one cognition (of object, person, group or symbol) and existing as a structured, relatively abiding element in individual character and social tradition. Separation anxiety: the fear and apprehension noted in infants when removed from the mother (or Dictionary of Psychology & Allied Sciences 375 surrogate mother) or when approached by stran gers. In later life, similar reactions may be caused by separation from significant persons or familiar surroundings. Separation-individuation: Psychologic awareness of one’s separateness, described by Margaret Mahler as a phase in the mother-child relationship that follows the symbiotic stage. In the separation individuation stage, the child begins to perceive himself as distinct from the mother and develops a sense of individual identity and an image of the self as object. Mahler described four subphases of the process: differentiation, practicing, rappro chement (active approach to ward the mother, repla cing the relative obliviousness to her that prevailed during the practicing period), and separation – individuation proper (awareness of discrete identity, separateness, and individuality). Serial-position effect: the observation that in memory experiments using a list of items to be remembered, items at the beginning and end of the list of remembered best. Many early cognitive models assu mes serial processing in, for instance, problem solving or the decoding of language, although recent evidence suggests that, in fact, information is often processed on several levels simultane ously (parallel processing). Serial reproduction: A technique for investigating constructive memory developed by Barlett, in which a first account is reproduced from memory, and so on. In this way, errors and alterations which occur in the accounts become cumulative, and therefore easier to classify and categorize. One everyday example of the use of serial reproduction is in the game ‘Chinese whispers’, in which a sentence or phrase is passed along a line of people, each person passing the message on by whispering 376 Dictionary of Psychology & Allied Sciences in to the ear of the next person. By the time the message reaches the end of the line, it has usually become completely dis to red. There is compelling evidence that is monoamine serves as a neurotransmitter substance in the central nervous system. It may play an important role in such diverse functions as sleep, sexual behaviour, aggressiveness, mo to r activity, perception (parti cularly pain), and mood. Dysfunction in central sero to nergic systems has been proposed as a cause or fac to r in various mental disorders, inclu ding schizophrenia and the affective disorders. Set may be demonstrated with most forms of cognitive process, but the most striking examples of it are perceptual set and learning set. In each case, information which is relevant to the prepared state is picked up far more quickly and easily that information which is not relevant. Set-weight: A pre-determined body weight, which seems to form the ‘natural’ weight of the animal concerned. The idea of set-weight arose from studies of the hypothalamus, in which it was observed that rats with lesions in particular areas of the hypothalamus would eat more than usual. At first it was thought that these areas represented ‘feeling centres’, but later findings showed that the increased intake only lasted until they had reached a certain body weight. Experimental lesions in other areas of the hypothalamus produced effects in the opposite direction: rats would cease to eat until their body weight had dropped to a certain point, whereupon Dictionary of Psychology & Allied Sciences 377 they would resume eating but eat only enough to maintain the new body weight. It has been suggested that similar mechanisms might be implicated in the case of obesity in humans. It is often more subtle than racism because it is likely to be based on assumptions about sex differences which are widely held in society. As many of these assumptions have been developed to justify an unfair treatment of women (see rationalization), sexism is often taken to mean discrimination against women. Sex-role behaviour: Behaviour which is influenced by the person’s beliefs about what is appropriate for members of their own sex. The term can also be used to refer to behaviour which conforms to society’s definition of appropriate gender beha viour. Sex-role learning: the processes by which a child or adolescent acquires an understanding of what is appropriate behaviour for their own sex, as oppo sed to appropriate behaviour for members of the other sex. Sex-role learning starts very early in life, and three-ears-olds have quite a clear ideas of which gender related behaviours their parents think are appropriate. Sex stereotypes: Beliefs which are held in the culture about sex differences and appropriate sex-role behaviour. Like all stereotypes they make a useful starting point to know what to expect from a person, but easily become misleading if used in preference to observing what the person is actually like.
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This work is not widely known mens health living discount casodex 50mg without a prescription, but it was the predecessor to prostate cancer natural cures buy casodex 50mg with visa the first edition of Little and Rubin (1987) androgen hormone values generic casodex 50mg visa, a book that established the term firmly in the mainstream statistical literature mens health december 2013 buy casodex overnight delivery. It is useful to prostate cancer biopsy procedure buy casodex 50 mg with visa know a bit of its remarkable his to ry, as some of the issues in multiple 25 26 Flexible Imputation of Missing Data imputation may resurface in contemporary applications. This section details his to rical observations that provide the necessary background. The birth of multiple imputation has been documented by Fritz Scheuren (Scheuren, 2005). The Census Bureau was then using (and still does use) a hot deck imputation pro cedure. Scheuren signaled that the variance could not be properly calculated, and asked Rubin what might be done instead. Rubin came up with the idea of using multiple versions of the complete dataset, something he had already ex plored in the early 1970s (Rubin, 1994). The original 1977 report introducing the idea was published in 2004 in the his to ry corner of the American Statisti cian (Rubin, 2004). According to Scheuren: “The paper is the beginning point of a truly revolutionary change in our thinking on the to pic of missingness” (Scheuren, 2004, p. Rubin observed that imputing one value (single imputation) for the miss ing value could not be correct in general. He needed a model to relate the unobserved data to the observed data, and noted that even for a given model the imputed values could not be calculated with certainty. His solution was simple and brilliant: create multiple imputations that refiect the uncertainty of the missing data. The 1977 report explains how to choose the models and how to derive the imputations. The idea to create multiple versions of the data must have seemed out rageous at that time. Drawing imputations from a distribution, instead of estimating the “best” value, was a drastic departure from everything that had been done before. Rubin’s original proposal did not include formulae for calcu lating combined estimates, but instead stressed the study of variation because of uncertainty in the imputed values. The idea was rooted in the Bayesian framework for inference, quite difierent from the dominant randomization based framework in survey statistics. Moreover, there were practical issues involved in the technique, the larger datasets, the extra works to create the model and the repeated analysis, software issues, and so on. These issues have all been addressed by now, but in 1983 Dempster and Rubin wrote: “Practi cal implementation is still in the developmental state” (Dempster and Rubin, 1983, p. Though several improvements have been made since 1987, the book was really ahead of its time and discusses the essentials of modern imputation technology. It provides the formulas needed to combine the repeated complete data estimates (now called Rubin’s rules), and outlines the conditions under which statistical inference under multiple imputation will be valid. Multiple imputation 27 Tests for combinations of parameters were developed by Li et al. Technical improvements for the degrees of freedom were suggested by Barnard and Rubin (1999) and Reiter (2007). Iterative algorithms for multivariate missing data with general missing data patterns were proposed by Rubin (1987, p. Additional work on the choice of the number of imputations was done by Roys to n et al. Fay pointed out that the valid ity of multiple imputation can depend on the form of subsequent analysis. He produced “counterexamples” in which multiple imputation systematically un derstated the true covariance, and concluded that “multiple imputation is in appropriate as a general purpose methodology. Related issues on the interplay between the imputation model and the complete-data model have been discussed by Rubin (1996) and Schafer (2003). Several authors have shown that Rubin’s estimate of the variance is biased (Wang and Robins, 1998; Robins and Wang, 2000; Nielsen, 2003; Kim et al. In response, Rubin (2003) emphasized that variance estimation is only an intermediate goal for making confidence intervals, and that the observed bias does not seem to afiect the coverage of these intervals across a wide range of cases of practical interest. He reasoned therefore that these findings do not invalidate multiple imputation in general. Reviews that criticize insuficient reporting practice of missing data started to appear in diverse fields (cf. Nowadays multiple imputation is almost universally accepted, and in fact acts as the benchmark against which newer methods are being compared. The major statistical packages have all implemented modules for multiple imputation, so efiectively the technology is implemented, almost three decades after Dempster and Rubin’s remark. The rightmost series corresponds to the number of publications per year that featured the search term “multiple imputation” in the title. These are often methodologi cal articles in which new adaptations are being developed. The series in the middle is the number of publication that featured “multiple imputation” in the title, abstract or key words in Scopus on the same search data. Scopus does not 28 Flexible Imputation of Missing Data 200 Early publications 100 ``Multiple imputation’’ in abstract 50 ``Multiple imputation’’ in title 20 10 5 2 1 1975 1980 1985 1990 1995 2000 2005 2010 Year Figure 2. The leftmost series is the number of publications in a collection of early publications available at This collection covers essentially everything related to multi ple imputation from its inception in 1977 up to the year 2001. This group also includes chapters in books, dissertations, conference proceedings, technical reports and so on. Perhaps the most in teresting series is the middle series counting the applications. The pattern is approximately linear, meaning that the number of applications is growing at an exponential rate. Suppose that we are interested in knowing the mean income Q in a given population. If we take a sample from the population, then the units not in the sample will have missing values because they will not be measured. It is not possible to calculate the population mean right away since the mean is undefined if one or more values are missing. The incomplete data perspective is a conceptual framework for analyzing data as a missing data problem. It is nevertheless sometimes useful to think what we would have done had the data been complete, and what we could do to arrive at complete data. The incomplete data perspec tive is general, and covers the sampling problem, the counterfactual model of causal inference, statistical modeling of the missing data, and statistical com putation techniques. For example, the data of a unit can be missing because the unit was excluded from the sample. Another form of intentional missing data is the use of difierent versions of the same instrument for difierent subgroups, an approach known as matrix sampling. Also, missing data that occur because of the routing in a questionnaire are intentional, as well as data. Though often foreseen, unintentional missing data are unplanned and not under the control of the data collec to r. Examples are: the respondent skipped an item, there was an error in the data transmission causing data to be missing, some of the objects dropped out before the study could be completed resulting in partially complete data, and the respondent was sampled but refused to cooperate. Item nonresponse refers to the situation in which the respondent skipped one or more items in the survey. Unit nonresponse occurs if the respon dent refused to participate, so all outcome data are missing for this respondent. His to rically, the methods for item and unit nonresponse have been rather dif ferent, with unit nonresponse primarily addressed by weighting methods, and item nonresponse primarily addressed by edit and imputation techniques. The distinction between intentional/unintentional missing data is the more important one conceptually. The item/unit nonre sponse distinction says how much information is missing, while the distinction between intentional and unintentional missing data says why some informa tion is missing. In Rubin (1987a), Y and R represent the data of the population, whereas in this book Y refers to data of the sample, similar to Schafer (1997). Rubin (1987a) uses X to represent the completely observed covariates in the population. Here we assume that the covariates are possibly part of Y, so there is not always a symbolic distinction between complete covariates and incomplete data. The symbol X is used to indicate the set of predic to rs in various types of models. Let Y denote the n fi p matrix containing the data values on p variables for all n units in the sample. The missing data are collectively denoted as Ymis, and contain all elements yij where rij = 0. However, the values of the part Ymis are unknown to us, and the observed data are thus incomplete. For a simple random sample, we could just take the sample mean Qfi as an unbiased estimate of the population mean Q. We will assume throughout this book that we know how to do the correct statistical analysis on the complete data Y. If we cannot do this, then there is little hope that we can solve the more complex problem of analyzing Yobs. Incompleteness can incorporate intentional missing data, but also unintentional forms like refusals, self-selection, skipped questions, missed visits and so on. If no data have been obtained for a unit i (presumably because of unit nonresponse), the ith record will contain only the sample number and perhaps administrative data from the sampling frame. The distri bution of R may depend on Y = (Yobs, Ymis), either by design or by happen stance, and this relation is described by the missing data model. Let fi contain the parameters of the missing data model, then the general expression of the missing data model is Pr(R|Yobs, Ymis, fi). The data Y = (Y, Y1 2) are drawn from a standard bivariate normal distribution with a correlation between Y1 and Y2 equal to 0. Missing data are created in Y2 using the missing data model eY1 eY2 Pr(R2 = 0) = fi0 + Y fi1 + Y fi2 (2. In prac tice, it is more convenient to work with the inverse logit (or logistic) function fi1 inverse logit (x) = exp(x)/(1 + exp(x)), which transforms a continuous x to the interval h0, 1i. The joint density func tion f(Yobs, R|fi, fi) of Yobs and R to gether depends on parameters fi for the full data Y that are of scientific interest, and parameters fi for the response indica to r R that are seldom of interest. Distinctness: the parameters fi and fi are distinct, in the sense that the joint parameter space of (fi, fi) is the product of the parameter space of fi and the parameter space of fi. For valid Bayesian inference, the latter condition is slightly stricter: fi and fi should be a priori independent: p(fi, fi) = p(fi)p(fi) (Little and Rubin, 2002, p. Note that the label “ignorable” does not mean that we can be entirely careless about the missing data. For inferences to be valid, we need to condition on those fac to rs that infiuence the missing data rate. A valid estimate of the mean of Y2 cannot be made without Y1, so we should include Y1 somehow in to the calculations for the mean of Y2.
The evidence suggests that this type of play is related to mens health boston cheap casodex 50 mg without a prescription children’s developing whole body and hand-eye co-ordination prostate cancer jokes buy casodex 50 mg free shipping, and is important in building strength and endurance (Pellegrini and Smith prostate 24 price casodex 50mg low price, 1998) prostate cancer gleason score 7 discount casodex master card. The most extensively researched aspect of physical play prostate cancer exam order cheap casodex on line, however, is ‘rough-and-tumble’ 18 play. It includes chasing, grappling, kicking, wrestling and rolling on the ground and appears to have evolved as a mechanism through which children learn to control aggression. It emerges slightly later than exercise play and is typical amongst pre-school children. However, like most types of play, it continues to be enjoyed, usually between family members and close friends, right in to adulthood. It is easily distinguishable from actual aggression by the evident enjoyment of the participants, and appears to be wholly beneficial. The research evidence suggests that it is clearly associated with the development of emotional and social skills and understandings. In human children, it is associated with the development of strong emotional bonds, or attachments, between children and their parents, and with school-aged children’s abilities to understand emotional expressions (Jarvis, 200). A study by Mellen (2002), for example, looked at father-son rough and tumble behaviours that involved direct body contact in 157 suburban families in the United States and found that it related very strongly with three-year-old sons’ social competence, as demonstrated in pre-school. There is a concern that children, largely as a consequence of the pressures of urban living discussed above, with the loss of natural environments and concerns about safety, are over supervised and do not have the opportunities for ‘risky’ outdoor physical play that supports their developing independence, resourcefulness and self-regulation. A general recognition of this concern is at the basis of pressures to provide outdoor play spaces for children living in urban environments. Amongst early years practitioners these concerns have led to a recent resurgence in the provision of outdoor play, and an increasing interest in Forest schools and the outdoor schools in some areas of Scandinavia (Tovey, 2007; Frost, 2010). Fine-mo to r play refers to a wide range of activities which support young children’s development of their fine-mo to r hand and finger co-ordination skills. These activities are often solitary, can be beneficially supported by an adult. Play with objects begins as soon as infants can grasp and hold on to them; early investigative behaviours include mouthing/biting, rotating while looking, rubbing/stroking, hitting and dropping. This might be described as ‘sensori-mo to r’ play when the child is exploring how objects and materials feel and behave. From around eighteen to twenty four months to ddlers begin to arrange objects, which gradually develops in to sorting and classifying activities. As with all other types of play, play with objects often also incorporates other types of play, as it clearly has physical and manipulative aspects and often, in children, is carried out within a pretence or socio-dramatic context. When young children are making or building, they are also often developing a s to ry or narrative. It is a relatively well-researched type of play, as it is distinctively related to the development of thinking, reasoning and problem solving skills. When playing with objects, children set themselves goals and challenges, moni to r their progress to wards them, and develop an increasing reper to ire of cognitive and physical skills and strategies. A study by Pellegrini and Gustafson (2005), for example, in which three to five year olds were systematically observed over an entire school year, demonstrated that the amount of playful exploration, construction and to ol use in which children engaged predicted their subsequent performance on physical problem-solving tasks. Play with objects is also particularly associated with the production of ‘private speech’, with children commonly commentating on their activity. This appears to have the function of helping the child to maintain their attention, keep their goals for the activity in mind, moni to r their progress, make strategic choices regarding ways to proceed, and generally regulate themselves through the task. As a consequence, construction and problem-solving play is also associated with the development of perseverance and a positive attitude to wards challenge (Sylva, Bruner and Genova, 1976). Symbolic play As we have discussed above, humans are uniquely equipped to use a wide variety of symbolic systems including spoken language, reading and writing, number, various visual media (painting, drawing, collage) music and so on. Not surprisingly, during the first five years of life, when children are beginning to master these systems, these aspects of their learning are an important element within their play. This type of play supports their developing technical abilities to express and reflect upon their experiences, ideas and emotions. Play with language starts very early in life with children under the age of one-year-old playing with sounds, and, as they grow older, particularly playing with the sounds of the language or languages they are hearing around them. This play is a very active process and quickly develops in to making up new words, playing with rhymes, and eventually young children’s love of puns and other jokes with language. Extensive research has clearly established that this type of play is a powerful support for developing language abilities and, crucially, through its support for phonological awareness, impacts upon the ease with which young children develop early literacy skills (Christie and Roskos, 2006). By placing basic numeracy in meaningful, real life contexts, play involving counting and other basic mathematical operations similarly supports young children’s ability to engage with formal mathematics with confidence (Whitebread, 2000; Carruthers and Worthing to n, 2006). Until fairly recently play with the various visual media had been relatively less systematically researched. Recent work, however, has strongly supported Vygotsky’s (1986) insight that there are very close links between early drawing and writing in young children’s mark making. In fascinating studies of mark making amongst chimpanzees, for example, Matthews (2011) has shown that drawing was perhaps the earliest evolving type of symbolic representation, and continues to be a significant aspect of young children’s 21 symbolic play. Studies of children’s drawings have demonstrated how through drawing, children gradually increase their ‘graphic vocabularies’, and their ability to organise graphic elements in to a pic to rial representation (a kind of ‘graphic grammar’), becoming increasingly able to use this mode of symbolic representation to express their meanings (Jolley, 2010; Ring, 2010). Musical play is another very under-researched area, despite being a ubiqui to us and highly significant form of play in all human cultures. From a very early age, children sing, dance and delight in exploring and making sounds of all kinds, with their own bodies and with all kinds of objects. In extensive research of early mother-infant pre-linguistic interactions, Trevarthen (1999) has clearly illustrated the role of the human infant’s innate response to rhythm and sounds in establishing early communicative abilities. A recent review of research in this area concluded that it seems likely that musical play, partly as a consequence of its powerfully social and interactive characteristics, supports a wide range of children’s developing abilities, including those related to social interaction, communication, emotion understanding, memory, self-regulation and creativity (Pound, 2010). In a study which involved 96 four-year-olds in joint music making, for example, Kirschner and Tomasello (2010) showed that these children significantly increased subsequent spontaneous cooperative and helpful behaviour, relative to a carefully matched control condition with the same level of social and linguistic interaction but no music. Pretence/socio-dramatic play In the urbanised, technologically advanced modern world, this is clearly the most prevalent type of play amongst young children, emerging around the age of one year old. High-quality pretend play has repeatedly been shown to be very closely associated with the development of cognitive, social and academic abilities. Studies have reported the impact of playworld experience on narrative skills in five to seven year olds (Whitebread and Jameson, 2010), of pretence play on deductive reasoning and social 22 competence, and of socio-dramatic play on improved ‘self-regulation’ among young children who are prone to be highly impulsive. A range of studies have supported Vygotsky’s (1978) insights concerning the impact of this type of play on children’s representational and self-regula to ry abilities (Karpov, 2005). This is also a type of play in which a high prevalence of ‘private speech’ is commonly observed (Berk, Mann and Ogan, 2006). Paradoxically, however, a number of studies have shown that, in fact, it makes some of the greatest demands on children’s self-restraint, or self-regulation. During socio dramatic play, in particular, children are obliged to follow the social rules governing the character they are portraying. Berk and colleagues report a number of studies with three and four year olds demonstrating a clear link between the complexity of socio-dramatic play and improvement in social responsibility. Findings revealed that the children participating in the play intervention, compared to a matched group who did not, showed a significant decrease in play deficits, became less socially disruptive and more socially connected with their peers. An aspect of socio-dramatic play which often causes concern amongst parents and teachers is that related to play with guns. However, the research evidence suggests that these concerns are misplaced and that attempts by adults to discourage or forbid them are generally counter-productive. Gun play, similar to rough-and-tumble, is easily distinguishable from real aggression or violence. In this kind of play, as in all other aspects of socio-dramatic play, children are developing their co-operative and social skills in contexts which are salient to their interests, and which arise from their real and vicarious experiences (Holland, 2003; Levin, 2006). Games with Rules Young children are strongly motivated to make sense of their world and, as part of this, they are very interested in rules. As a consequence, from a very young age, they enjoy games with rules, and frequently invent their own. Opie and Opie’s (1959) collections of children 23 games and folklore are a testament to children’s love of games with rules. These include physical games such as chasing games, hide-and-seek, throwing and catching etc. As well as helping children to develop their understandings about rules, the main developmental contribution of playing games derives from their essentially social nature. While playing games with their friends, siblings and parents, young children are learning a range of social skills related to sharing, taking turns, understanding others’ perspectives and so on (DeVries, 2006). The use of electronic and computer games by to day’s children is another particular area of anxiety for parents and teachers. A recent survey of 346 children from the 7th and 8th grade of seven elementary schools in the United States, for example, found that playing videogames did not appear to take place at the expense of children’s other leisure activities, social integration, and school performance. There was also no significant relationship between the amount of time children spent on videogames and aggressive behaviour. Furthermore, a positive relationship was found between time spent on videogames and a child’s intelligence (Van Schie and Wiegman, 1997). These consist of environmental and social fac to rs which support or inhibit children’s natural playfulness and fac to rs related to provision of opportunities. A range of evidence has indicated that playfulness in children is both an indication of mental well-being and is supported by it. In this literature the two key issues which emerge relate 24 to young children’s formation of secure emotional attachments and to the role of stress. Of particular importance in this area is the crucial role of playfulness in children’s formation and maintenance of friendships, which are, in turn, fundamentally important in supporting healthy social and emotional development (Panksepp, 2007). The role of secure emotional attachments in supporting children’s ability to cope with anxiety and stress is also of particular significance. However, here the picture is quite complex, as a certain level of stress or unpredictability in the environment appears to support the development of children’s resilience and playfulness, whereas high levels of stress clearly lead to a reduction in the amount of play in which children engage (Burghardt, 2005). Lester and Russell (2010) have provided a powerful analysis of the ‘environmental stressors’ experienced by children across the world. From this analysis it is clear that some of the most vulnerable groups of children are those living in cities and urbanised contexts. Children living in poverty in these environments are often malnourished, a situation which, since playfulness requires metabolic energy (Burghardt, 2005), is often associated with low levels of play. As a consequence of the stress on their parents, they are also less likely to receive sensitive parenting leading to secure attachments. Meltzer et al (2000) estimated that children 25 living in low-income households are nearly three times as likely to suffer mental health problems. Living in urban environments can also have negative effects on the playfulness of children who are fortunate to live in supportive households, but whose parents, carers and teachers, perceiving a range of environmental hazards and dangers, become overly risk-averse and over-protect and over-supervise their children (Veitch et al, 2006). This leads us in to the second category of fac to rs which can support or inhibit children’s play, which relate to opportunities provided for play. While the children in Nicaragua enjoyed a high level of independent mobility and developed self-reliance attitudes to wards safety while swimming in lakes, climbing trees etc. This problem of parental over-supervision and over-scheduling of children has arisen quite recently, just in the last few decades. However, according to a survey of parental attitudes in sixteen countries (Singer et al. Mothers in this survey, from countries across Europe and in four other continents, reported fears about allowing their children to play outside related to increases in traffic, crime, harassment and violence, possible abduction, dirt and germs, and many more similar issues.