In a study of the effect of college student employment on academic performance, the following summary statistics for GPA were reported for a sample of students who worked and for a sample who did not work.( university of central florida undergraduate research journal, spring 2005).
sample s. gpa standard d
students employed, 184, 3.12, .485
not employed 114, 3.23, .524
the samples are selected at random from working and nonworking students at the University of Central Florida. Does this information support the hypothesis that for students at this university, those who are not employed have a higher mean GPA than those who are employed ( significance level =.05)?
statistics - PsyDAG, Thursday, April 21, 2011 at 10:56am
Z = (mean1 - mean2)/standard error (SE) of difference between means
SEdiff = √(SEmean1^2 + SEmean2^2)
SEm = SD/√(n-1)
If only one SD is provided, you can use just that to determine SEdiff.
Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion related to your Z score.