Howdy! Great question: z-tests are useful insofar as you know the population mean/standard deviation. Many times, we might know the pop mean, but not the std dev. If you don't know the std dev, you have to do a one-sample t-test. If the sample distribution is not normal, then you violate the assumption for t-tests. It doesn't mean you can go back to using a z-score, however, because we're estimating the sample std dev. We have to go for a nonparametric test in this case, so we do not make a Type I error.
Dear Prof. Swan I could not find the episode #5, is it actually missed on youtube?
Not sure why it wasn't available for you, but here it is! ua-cam.com/video/M0N-v6W-7P4/v-deo.html
Where i can use your .csv files
Most of them are available in JASP upon download. Other ones I use in videos that aren’t linked in the description are not shareable.
Why did you not use Z test and only use wilcoxon and student .. at 8.46 so you found that its not normal and decided to use wilcoxon why not z test ?
Howdy! Great question: z-tests are useful insofar as you know the population mean/standard deviation. Many times, we might know the pop mean, but not the std dev. If you don't know the std dev, you have to do a one-sample t-test. If the sample distribution is not normal, then you violate the assumption for t-tests. It doesn't mean you can go back to using a z-score, however, because we're estimating the sample std dev. We have to go for a nonparametric test in this case, so we do not make a Type I error.
@@AlexanderSwan thank you sir