Dear SPMer,
I am interesetd in evakuation of "difference of difference".
If you want to know the changes from the baseline,
you might do comparisons as follows:
1) Group A (activation) - Group A (rest).
2) Group B (act) - Group B (rest)
or, 1) Aact - Arest
2) Bact - Brest
If you would like to know the difference between
the two activations in Groups A and B, you might
do comparison such as,
"(Aact - Arest) - (Bact - Brest)"
that is,
= "Aact - Arest - Bact + Brest"
My question is "Is it the right way to do this comparison
by typing in the box of study design as
"1 -1 -1 +1". ?
Thank you in advance
Manabu
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Manabu TASHIRO M.D. Ph.D.
Division of Clinical Pharmacology
Tohoku University Graduate School of Medicine
2-1 Seiryo-machi, Aoba-ku, Sendai
980-8575 Japan
TEL: +81-22-717-8059 or 8057
FAX: +81-22-717-8208
Email: [log in to unmask]
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