I am going to give you three possible solutions to your problem, if
none of these work, then get back to me and we will find another.
1. First, you might be surprised to hear that regression does not
assume that either the DV or the IVs are normally distributed.
Rather, it assumes that the residuals are normally distributed. The
easiest way to check this is to click on plots from the main
regression dialog, and ask for a histogram or a normal probability
plot. This might show that you don't have a problem.
2. If you still have a problem, you might be able to transform your
DV. If you have positive skew (i.e. lots of low values, not many
high, common in reaction time, or finance) then try a log transform -
this might solve the problem. If you have negative skew, try a square
transform.
3. If your skew is very serious, you could consider recoding into a
series of values, e.g. if it is salaries, you might split into 10
groups.
4. If we are desperate, we could try bootstrapping, although this is
a bit tricky.
5. If we are more desperate and you have a large sample, we could try
a technique that doesn't require normality, or is robust against it.
We probably want to avoid this though.
That was more than three, wasn't it? Let me know if that works, or
doesn't work, and we will have another go.
jeremymiles-ga
p.s. I can provide some links or recommendations for further reading.
Are you based in a university where you have access to a library? |