Psych220 Chap 9

Front 1

t statistic

Back 1

is used to test hypotheses about an unknown population mean when the value of the standard deviation is unknown. the formula for the t statistic has the same structure as the z score formula, except that the t statistic uses the estimated standard error in the denominator

Front 2

degrees of freedom

Back 2

describes the number of scores in a sample that are independent and free to vary. because the sample mean places a restriction on the value of one score in the sample, there are n-1 degrees of freedom for the sample

Front 3

t distribution

Back 3

this is the complete set of t values computed for every possible random sample for a specific sample size (n) or a specific degrees of freedom (df). the t distribution approximates the shape of a normal distribution

Front 4

r squared (the percentage of variance accounted for)

Back 4

a measure of effect size that determines what portion of the variability in the scores can be accounted for by the treatment effect

Front 5

estimated standard error

Back 5

an estimate of the standard error that uses the sample variance (or standard deviation) in place of the corresponding population value

Front 6

T test conditions: what conditions contribute to a larger likelihood of rejecting a null hypothesis

Back 6

a larger sample size and smaller sample variance contribute to a larger likelihood of rejecting a null hypothesis