A multinomial logit model (N=192) revealed (besides others) the
following statistics for the outcome, y, and one predictor, x:
- y = A (baseline, n=34)
- y = B (n=26), B(x)=0.7323 (SE=0.2384)
- y = C (n=132), B(x)=0.6535 (SE=0.2041)
With a t-test I want to explore whether the two predictors differ
significantly, and I use the following calculation (according to
Bortz, 2005, p.140):
##########
dm <- 0.7323 - 0.6535
se.dm <- sqrt( (0.2384 / (34 + 26)) + (0.2041 / (34 + 132)) )
t.val <- dm / se.dm
pval <- (1 - pt(t.val, df=(34+26+132) )) * 2
##########
My question is where this calculation is wrong and why.
Ref.: Bortz, J. (2005). Statistik für Human- und
Sozialwissenschaftler (6. Aufl). Berlin: Springer.
--
Sascha Vieweg, saschav...@gmail.com
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