PSYC209 Lecture 8: Testing Means - One Sample t-Test With Confidence Intervals
8 Feb 2017
School
Department
Course
Professor
Document Summary
Inferential statistics used to determine the number of standard deviations in a t distribution that a sample mean deviates from the mean value or mean difference stated in the null hypothesis. Has greater variability in the tails because the sample variance is not always equal to the population variance. The t distribution shares the same characteristics as the normal distribution. The t distribution is associated with degrees of freedom (df: n-1. Compared to z test, for t test we do not know the population variance. Gives an estimate of the size of an effect in the population. Three measures of effect size: cohe(cid:374)"s d, eta squared and omega squared -> two measures of proportion variance. Proportion variance is a measure of effect size in terms of the proportion or percent of variability in a dependent variable that can be explained or accounted for by a treatment.
