You are right. Actually I am doing difference-in-differences model. There are two ways to do that: one using Proc Glm that can be performed with wide-format data. another way is using proc mixed that needs long format of data. I knew that the results should be similar. However, because i did not get good result with proc glm, I though just in case is good to try proc glm, that is why I asked for that. Thanks ... View more