Cohen’s d critical value of t degrees of freedom (df) effect size (d) replicate r2 single-sample t test underpowered | a statistical test that compares a sample mean to a population mean when the population standard deviation is not known. to repeat a study, usually introducing some change in procedure to make it better. a standardized measure of effect used to measure the difference between means. an effect size that calculates how much of the variability in the outcome variable is accounted for by the predictor variable. the number of values in a sample that are free to vary. a measure of the degree of impact of the independent variable on the dependent variable. value of t used to determine whether a null hypothesis is rejected or not; abbreviated tcv. term for a study with a sample size too small for the study to have a reasonable chance to reject the null hypothesis given the size of the effect. |