Medicine and Health Sciences Commons^™

Neuroendocrine Aspects Of Primary Endogenous Depression Xv. Mathematical Modeling Of Nocturnal Melatonin Secretion In Major Depressives And Normal Controls, L. Kathleen Sekula, Joseph F. Lucke, E. Kevin Heist, R. Kenneth Czambel, Robert T. Rubin

Joseph Lucke

We previously reported a trend toward a higher mean nocturnal serum melatonin (MEL) concentration, based on 30-min blood sampling over 24 h, in 23 female definite endogenous depressives compared to 23 matched normal female control subjects, and no significant difference in 15 male depressives compared to their controls (Rubin et al., 1992). In both groups of patients vs. their controls, there also were trends toward an earlier MEL rise time, by about 30 min, and a later MEL peak time, by about 90 min. Because the offset of MEL secretion was not estimated in that study, the total duration of …

Student's T-Test And The Glasgow Coma Scale, Joseph Lucke

Joseph Lucke

Study Objective: To explore how Student's t test, which assumes normal errors, is affected by the nonnormal distribution of Glasgow Coma Scale (GCS) scores.

Methods: A sample of 145,295 GCS scores from the Pennsylvania Trauma Systems Foundation was assumed to represent the true GCS distribution. Four Monte Carlo simulations, each based on 40,000 replications, were conducted to approximate the distribution of t values arising from samples drawn from the GCS distribution, using sample sizes of 10, 30, 60, and 100 per group.

Results: The histograms of t values derived from the GCS distribution resembled the corresponding Student t distributions for …

The Biases And Mean Squared Errors Of Estimators Of Multinormal Squared Multiple Correlation, Joseph F. Lucke, Susan E. Embretson

Joseph Lucke

The sample squared multiple correlation coefficient, $R^{2}$ is known to have certain unsatisfactory properties as an estimator of the population squared multiple correlation. Hence, numerous adjusted estimators based on functions of $1-R^{2}$ have been proposed. We examine the biases and mean squared errors of five adjusted estimators as well as $R^{2}$. General results are given for estimators linear in $1-R^{2}$, and four such estimators are examined in detail. In addition, a quadratic estimator and the minimum variance unbiased estimator are examined. Comparisons among these estimators are made in terms of absolute bias and mean squared error.