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Anyone know why when you run a SEM model in SAS using proc calis (or tcalis) you do not get p-values for the parameter estimates? It does supply a t-value however.

Two popular SEM packages in R, 'sem' and 'lavaan', both give p-values for the estimates but they use a Z test statistic.

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I am not an expert on SAS or SEM, but if you get t-values, can't you calculate p-values yourself? –  mpiktas Jan 11 '11 at 4:24
    
Yes which is what I do, but in every other SAS procedure the p-value is given along with the test statistic. –  Glen Jan 11 '11 at 14:46
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up vote 2 down vote accepted

@mpiktas is right and knowing the value of the test statistic ($t$ or $z$) allows you to know which parameter estimate is significant at the desired $\alpha$ level. In practice, the $t$-statistic is equivalent to a $z$-score for large samples (which is often the case in SEM), and the significance thresholds are 1.96 and 2.58 for the .05 and .01 $\alpha$ levels. Most of the time, $p$-values are interesting when comparing models; as shown in this nice tutorial on Structural equation modeling using SAS, by Y H Chan, giving $t$- or $z$-statistic with associated critical values at 5% should be enough, IMO.

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Thanks. I should have made it clear that I know how to calculate a p-value given a test statistic but I find it strange that they don't output the p-value for you as in almost all the other SAS procedures. –  Glen Jan 11 '11 at 14:47
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