Resolved: How can I know if a one-sided test is left-tailed or right-tailed? Please help
5.7.+Test+for+the+mean.+Dependent+samples_exercise
"Some guy on the internet designed a weight-loss program. You are wondering if it is working. You are given a sample of some people who did the program. You can find the data in kg if you prefer working with kg as a unit of measurement." This is what the exercise is asking
The Quick P-value calculator provided by 365 Datascience asks for the type of the hypothesis test. I knew how to differentiate between one-sided and two-sided tests, but I dont know how to determine the left-tailed and right-tailed one. Please help me with this asap, thank you!
Hi Huyen!
Thanks for reaching out!
To determine if a one-sided test is left-tailed or right-tailed, look at the alternative hypothesis. A right-tailed test is used if the alternative hypothesis states that the parameter is greater than a certain value, placing the critical region in the right tail. Conversely, a left-tailed test is used if the alternative hypothesis states that the parameter is less than a certain value, placing the critical region in the left tail.
For the given situation, where you want to determine if the weight-loss program is effective, you need to compare the weights of individuals before and after the program. This typically involves testing if there is a significant decrease in weight after the program. Therefore, this would be a left-tailed test because you are testing if the mean weight after the program is less than the mean weight before the program (stated in the alternative hypothesis).
Hope this helps.
Best,
Ivan