Two questions about marketing research

1. There are 3 chi-square tests – The goodness of fit test, the test of independence, and the test for homogeneity. What’s the difference among the three? Why would you use one over another?

2. There are one-sampled and two-sampled t-tests and BOTH can be either one-tailed or two-tailed. When is a t-test one-tailed? When is it two-tailed? Can you give me examples for both?