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There is no p-value map. Rather, you create contrasts (after you estimate the model) that create either: (1) spmT_ and con_ images or (2) spmF_ and ess_ images. The con_ images provide you with a measure of the magnitude of the contrast. The spmT_ and spmF_ images provide you with either the T-statsistics and F-stastistics at each voxel. From those values, you can determine the p-value.

The ess_ is the extra sums of squares associated with the numerator for the F-test.

For a general introduction, I'd read up on statistics and the general linear model. All of the classical analyses in SPM use the general linear model.

Best Regards, Donald McLaren
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D.G. McLaren, Ph.D.
Postdoctoral Research Fellow, GRECC, Bedford VA
Research Fellow, Department of Neurology, Massachusetts General Hospital and Harvard Medical School
Office: (773) 406-2464
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On Fri, May 13, 2011 at 8:28 AM, 王媛 <[log in to unmask]> wrote:
Hello,
 
Just a simple question as the subject.
The second level analysis produces a lot of files, I wonder which one contains or is the p-value map.
RPV? mask? ResMS?
And what exactly does the p-value map show? Is it simply a mask which sets '1s' for the pixels larger than the value,'0s' for others?
I am totally a freshman for the analysis procedure, maybe you can explain in a easier way:)
Thank you so much.
 
Best Regards,
Yuan