Hi Chen,
You talk about confidence intervals and p-values, and how you can get those for other combinations/comparisons of levels. The answer about p-values I have given recently, here. With regards to confidence intervals I'm not sure I can give you a satisfying answer, but I first want to ask you to clarify your question a bit more. Do you mean the confidence interval of the difference between level 1 and level 2, for example? There are ways to calculate this, but I'm not sure if this is at all useful in practice. I found it hard to determine a best way of doing this, and I found I had very little need for it in the end, so I never figured out exactly how to do it.
If you could explain what kind of confidence bounds you are talking about, exactly, and what you want to use them for, I can see if I can help you.
Best,
Paul
