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Biomedical subjects

P McGrain

Publications and source records attributed to P McGrain.

3 recordsLinked to original sources

Relationship between multiple predictor variables and normal knee torque production.

The purpose of this study was to develop predictive models relating isokinetic knee testing performance to anthropometric and demographic variables. The subjects were 134 healthy volunteers (70 female, 64 male) between the ages of 10 and 80 years. The investigators measured subjects' peak knee flexion and extension torque production at two angular velocities. Stepwise regression analyses were used to examine the relationship between each torque-dependent variable and the following potential predictor variables: age, sex, side of lower extremity dominance, height, weight, percentage of body fat, and thigh girth. The investigators generated two sets of models designed to predict preinjury knee strength. Clinicians can use one set of models by assessing predictor variables before or immediately following injury. The second set of models involves the assessment of predictor variables postinjury, excluding an assessment of percentage of body fat and thigh girth. The results indicated that peak knee torque production can be predicted with statistically significant accuracy (multiple R = .78-.87). The predictive models generated in this study can be used to establish muscle strength goals for patient rehabilitative programs.

Adolescent

Nonparametric testing using the chi-square distribution.

We have described three separate uses of the chi-square distribution: comparing observed and expected frequency distributions of a nominal variable, testing for the independence of two variables, and using the chi-square test in determining correlation coefficients. We hope this paper has helped you gain an understanding of the uses of the chi-square test and the steps required to calculate this statistic.

Humans

Comparing two sample means t tests.

The t test is used to test for differences in means or to test a criterion measure between two groups of scores. Whether an investigator designs a study where the subjects' scores from one group are independent of the scores in the other group (independent t test), the basic assumptions of the test are identical. Hence, the subjects' scores from each group are assumed to be normally distributed and the variance of the two groups of scores are assumed to be homogeneous. The basic differences between the independent t test and the correlated t test are in calculating the t statistic and the df and in the method in which subjects are assigned to each group. If an investigator uses the same subjects in each group, then the correlated t test must be used. If subjects are matched or paired by some related variable, such as age, height, or weight, then the correlated t test should be used. In all other cases, the independent t test would be appropriate.

Electromyography