Dear SPM experts,
In order to plot the contrast estimates of my 2nd Level, I open a particular contrast in SPM and go to a local peak maxima. Before so and in addition to this contrast, I have defined a contrast named "Effect of interest" (thereafter eoi) using an F contrast and writing the vectors' weights in the columns to reduced design. Since my design matrix has 6 columns, I specified the eoi contrast as 7:maximum. This is the contrast I will use to plot the contrast estimates.
Next I choose Plot in the SPM window and Contrast estimates and 90% C.I. Then I select the eoi contrast and get the contrast estimates from that coordinate. So far so good.
My question is: what mathematical operation applies SPM to the beta coefficients of this contrast to compute the contrast estimates displayed in this plot?
I'd appreciate any help to being able to calculate the contrast estimates that SPM provides in the structure contrast of the matlab workspace using the beta values.
Many thanks in advance for your assistance.
Kind regards,
Noelia MartÃnez-Molina
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