The behaviour of group sequential tests in the two-sample problem is investigated if one replaces the classical non-robust estimators in the t-test statistic by modern robust estimators of location and scale. Hampel's 3-part redescending M-estimator 25A used in the Princeton study and the robust scale estimators length of the shortest half proposed by Rousseeuw & Leroy and Q proposed by Roussee...

Ask experts what would be an important reduction in amount consumed. Need some idea of the SD of a within-child difference in consumption from a four hour period in one day to a four hour period in another day. Could do a pilot study with say 10 children measured [without any intervention] on two different days and get the SD of the 10 differences. Then use sample size formula for 1 sample t-te...

OBJECTIVE To provide a practical guidance for the analysis of N-of-1 trials by comparing four commonly used models. METHODS The four models, paired t-test, mixed effects model of difference, mixed effects model and meta-analysis of summary data were compared using a simulation study. The assumed 3-cycles and 4-cycles N-of-1 trials were set with sample sizes of 1, 3, 5, 10, 20 and 30 respectiv...

The Kids and Communities Count Farm Safety Lesson is a follow-up to our Kids Count Lesson that used the North American Guidelines for Children's Agricultural Tasks (NAGCAT) and was previously delivered to nearly 2,000 fifth-grade students in Hillsborough County, Florida. This year, the lesson was administered in two migrant schools and included a parent survey and a presentation of the lesson i...

Materials and Methods: This Randomized Control Trial consists of two experimental and control groups. The experimental group received intervention based on Health Action Model. Control group did not receive any intervention except participating in the current safety courses of company. The sample size was 270 worker who were randomly selected and divided into two experimental (n=135) and contro...

The importance of sample size evaluation in clinical trials is reviewed and a general method is presented from which specific equations are derived for sample size determination or the analysis of power for a wide variety os statistical procedures. The method is discussed and illustrated in relation to the t test, tests for proportions, tests of survival time, and tests for correlations as they...

Normatively, a statistical pairwise comparison is a function of the mean, standard deviation (SD), and sample size of the data. In our experiment, 203 undergraduates compared product pairs and judged their confidence thatone product was better than the other. We experimentally manipulated (within subjects) theaverage productratings, the number of raters (sample size), and the SD of the ratings....