st: pseudo r-square 4-level-logit-regression xtmelogit vs gllamm

[Martina Brandt <brandt@soziologie.uzh.ch>]

dear list,

mc kelvey and zavoina suggest an r2 for multilevel logit regression, 
which is the variance of the predicted probabilities divided by the 
total variance of the model (=proportion of explained variance). in the 
four level model this would be 
(var(phat))/((var(phat)+((pi2)/3))+var(level2)+var(level3)+var(level4))
(see snijders & bosker 1999: 225).
using gllamm i always had pseudo r2 around 0.20, and now using xtmelogit 
it is supposed to be only around 0.01. does anyone have an idea, why 
this could have happened and how these differences could be explained?

thanks! martina
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