APA Dictionary of Psychology

a t test used to analyze data from a between-subjects design, in which the different groups of individuals or other entities measured are not associated with one another. In the independent-samples t test, one calculates the value of the test statistic t from the means, standard deviations, and sizes of the two groups of interest, then compares its value to a t distribution for a given degree of freedom under the assumptions of normality and independence of observations, among others. Also called independent-measures t test. Compare dependent-samples t test.