PubMed · 9240996
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J E Kuhn, M L Greenfield, E M Wojtys. A statistics primer. Statistical tests for discrete data.. https://doi.org/10.1177/036354659702500425
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Optimal design of quantitative-trait loci (QTL) mapping studies requires a precise understanding of the power of QTL linkage versus QTL association analysis, under a range of different conditions. In this article, we investigate the power of QTL linkage and association analyses for simple random sibship samples, under the variance-components model proposed by Fulker et al. After a brief description of an extension of this variance-components model, we show that the powers of both linkage and association analyses are crucially dependent on the proportion of phenotypic variance attributable to the QTL. The main difference between the two tests is that, whereas the power of association is directly related to the QTL heritability, the power of linkage is related more closely to the square of the QTL heritability. We also describe both how the power of linkage is attenuated by incomplete linkage and incomplete marker information and how the power of association is attenuated by incomplete linkage disequilibrium.
PURPOSE: The aims were to describe the functional abilities of and services provided to stroke patients not admitted to hospital a year after stroke and to investigate factors associated with receiving rehabilitation services. METHOD: A cohort of stroke patients who had not been admitted to hospital were notified by general practitioners. Patients were assessed at a month and a year after stroke on measures of impairment and disability. The rehabilitation received was recorded. There were 124 stroke patients notified by GP's who had not been admitted to hospital. Of these 70 were assessed at both one month and one year after stroke. RESULTS: Patients showed persistent impaired levels of disability one year after stroke, as measured by the Extended Activities of Daily Living (EADL) scale. There was no significant improvement in Barthel scores and only a slight improvement on the EADL from one month to one year after stroke. There were no patients with severe mobility or severe arm impairment. Most patients had some cognitive impairment but there was no significant change between a month and a year. The provision of rehabilitation services increased between a month and a year after stroke. Rehabilitation was provided to those patients with impaired motor function. CONCLUSIONS: Stroke patients not admitted to hospital have significant levels of disability which does not change substantially in the year after stroke. Rehabilitation was provided on the basis of physical function, rather than cognitive function.
BACKGROUND: The first imaging evaluation of the child with urinary tract infection (UTI) is often the same for all children, regardless of the child's clinical presentation. However, this approach is simplistic and ignores considerable differences in the frequency of abnormal pathophysiology in different subpopulations of children with UTI. OBJECTIVE: Six clinical variables are evaluated as predictors of vesicoureteral reflux (VUR) in a large series of girls with UTI. MATERIALS AND METHODS: Data were collected from a consecutive series of 919 girls undergoing a first imaging evaluation for UTI. Six input variables were used: age, maximum body temperature (T(max)), number of UTIs, hospitalization, family history of childhood UTI, and rapidity of response to antibiotic therapy. The dependent variable was VUR. Data were enumerated and analyzed by logistic regression and the chi-square test. RESULTS: VUR was present in 28.8 %. The percentage with VUR varied from 56.1 % for age < 6 months and T(max) L 38.5 degrees C to 13.0 % for age L 10 years and T(max) < 38.5 degrees C. The frequency of VUR was significantly lower in girls with T(max) < 38.5 degrees C in most age groups. Logistic regression demonstrated, when all clinical variables were taken together, that only age and T(max) were independent predictors of VUR. CONCLUSIONS: Girls with UTI should not be considered to be a homogeneous group. The frequency of VUR is related to T(max) and inversely to age. Data about these subpopulations should be used in deciding which girls should undergo cystography.