[R] difference between lrm's Model L.R. and anova's Chi-Square

2008-03-02 Thread johnson4
I am running lrm() with a single factor. I then run anova() on the fitted model to obtain a p-value associated with having that factor in the model. I am noticing that the Model L.R. in the lrm results is almost the same as the Chi-Square in the anova results, but not quite; the latter value is

Re: [R] difference between lrm's Model L.R. and anova's Chi-Square

2008-03-02 Thread johnson4
Quoting Frank E Harrell Jr [EMAIL PROTECTED]: anova (anova.Design) computes Wald statistics. When the log-likelihood is very quadratic, these statistics will be very close to log-likelihood ratio chi-square statistics. In general LR chi-square tests are better; we use Wald tests for speed.

Re: [R] difference between lrm's Model L.R. and anova's Chi-Square

2008-03-02 Thread Frank E Harrell Jr
[EMAIL PROTECTED] wrote: Quoting Frank E Harrell Jr [EMAIL PROTECTED]: anova (anova.Design) computes Wald statistics. When the log-likelihood is very quadratic, these statistics will be very close to log-likelihood ratio chi-square statistics. In general LR chi-square tests are better; we

[R] difference between lrm's Model L.R. and anova's Chi-Square

2008-03-01 Thread johnson4
I am running lrm() with a single factor. I then run anova() on the fitted model to obtain a p-value associated with having that factor in the model. I am noticing that the Model L.R. in the lrm results is almost the same as the Chi-Square in the anova results, but not quite; the latter value is

Re: [R] difference between lrm's Model L.R. and anova's Chi-Square

2008-03-01 Thread Frank E Harrell Jr
[EMAIL PROTECTED] wrote: I am running lrm() with a single factor. I then run anova() on the fitted model to obtain a p-value associated with having that factor in the model. I am noticing that the Model L.R. in the lrm results is almost the same as the Chi-Square in the anova results, but