Good morning, everyone. I’m having trouble understanding the Z-Score test statistic. In the reading, a few examples, and the equation for calculating the Z-Score are shown as follows: Z = (Sample Mean - Population Mean) / Standard Deviation but there is another equation as follows: Z = (Sample Mean - Population Mean) / Standard Error What is the difference between the two equations? In what scenario is each used? If someone could help elabrote I would appreciate it. Thanks so much, Sean

std error = std deviation / sqrt(n) 30, you can use z-statistic. Otherwise u need to use the t-statistic.

Thanks CP.

Thx cpk, I had the same question