Analyze data from experiments, quasi-experiments, and comparing groups
T-test (used to compare groups) - replaces z-test
T-test of the means of groups. Use the t-test when the population standard deviation is unknown (sigma).
Sample compared to population:
T = sample mean - population mean divided by standard error
df = degrees of freedom, typically n-1
Sample compared to sample:
T = sample1 mean - sample2 mean divided by standard error
df = n1 +n2 - 2
Pre-post comparison: (repeat measures format)
Page 335 for formula
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