Z-Test and Effect Size

Topic 9

what is the null hypothesis statement for a Z-test?

sample mean = population mean

what is the alternative hypothesis for a one tailed test?

sample mean > population mean or sample mean < population mean

what is the alternative hypothesis for a two-tailed test?

sample mean does not equal population mean

what are the assumptions of a one-sample Z-test?

population SD is known, data are independent, sample size is large (n greater than or equal to 30) or the sample comes from a normal distribution n<30

what does cohen’s d tell us?

quantifies the difference between two means in terms of SDs

what does effect size do?

measures the magnitude of the difference, independent of sample size, shows practical significance

what does a z-test do?

compares the sample mean to a known population mean