Most of the time, we have the raw data to conduct the necessary statistical analysis in SAS®. However, when there is only summary data available, some additional SAS coding is necessary in order to perform the hypothesis test. SAS procedures, as well as simplified macros (%SUM_TTEST, %SUM_ANOVA, %P_ANOVA, %SUM_CHI) with examples, will be discussed in this paper for chi-square test, two sample t...

In neuropsychological single-case studies, a patient is compared with a small control sample. Methods of testing for a deficit on Task X, or a significant difference between Tasks X and Y, either treat the control sample statistics as parameters (using z and zD) or use modified t tests. Monte Carlo simulations demonstrated that if z is used to test for a deficit, the Type I error rate is high f...

We develop an approach for microarray differential expression analysis, i.e. identifying genes whose expression levels differ between two or more groups. Current approaches to inference rely either on full parametric assumptions or on permutation-based techniques for sampling under the null distribution. In some situations, however, a full parametric model cannot be justified, or the sample siz...

Many methodologies to decrease stress in adolescents have been introduced and implemented. However, it seems that the problems in their physical, mental, emotional, and learning conditions still exist, especially for long-term. The proposed program with some booster was used to solve the long run problems. To examine the effectiveness of program developed from cognitive-experiential self-theory...

-The aim of this research was to compare the ego strength of addicted and non addicted people. The sample size of 200 men (100 addicts+ 100 non addicts) living in Karaj and Tehran cities of Islamic Republic of Iran that was selected through the availability sampling. To collect data, a 52-item BESS (Barrons ego strength scale) questionnaire was used. Averages and t test were applied as statisti...

There is growing interest in the role of the oxytocin system in social cognition and behavior. Peripheral oxytocin concentrations are regularly used to approximate central concentrations in psychiatric research, however, the validity of this approach is unclear. Here we conducted a pre-registered systematic search and meta-analysis of correlations between central and peripheral oxytocin concent...

BACKGROUND During the last 30 years, the median sample size of research studies published in high-impact medical journals has increased manyfold, while the use of non-parametric tests has increased at the expense of t-tests. This paper explores this paradoxical practice and illustrates its consequences. METHODS A simulation study is used to compare the rejection rates of the Wilcoxon-Mann-Whi...

Injury Prevention recently published a commentary critical of epidemiological approaches to cycling safety. The author, Kary, suggests that our paper, which reanalysed Walker’s study of motor vehicle overtaking distance for cyclists, made false claims about type I errors and confused statistical significance and clinical significance. Kary supports this critique, along with other points in the ...

Positive Darwinian selection at the molecular level is often studied by comparing the number of synonymous nucleotide substitutions per synonymous site (d,) and the number of nonsynonymous substitutions per nonsynonymous site (dN) between homologous gene sequences, and a t-test with an infinite number of degrees of freedom is usually used for determining the statistical significance of the diff...

The most elementary statistical test is the paired samples t-test with just two pairs. Here the data set to be analysed consists of two numbers (the two paired differences), and the statistical test examines whether the population mean is zero. This test can be derived in a surprisingly fast and intuitive manner by plotting one number against the other on a piece of graph paper, then joining th...