Date:         Tue, 15 Mar 2005 10:26:32 -0600
Reply-To:     Debarchana Ghosh <drg999@ksu.edu>
Sender:       "SPSSX(r) Discussion" <SPSSX-L@LISTSERV.UGA.EDU>
From:         Debarchana Ghosh <drg999@ksu.edu>
Subject:      Re: Applicability of Hosmer-Lemeshow?
Comments: To: Jonathan Woodring <jonathan.woodring@umb.edu>
In-Reply-To:  <DB33CB380BDB6A43A06FF44519FB4005072EA146@ems4.umassb.net>
Content-Type: text/plain; charset=ISO-8859-1

> Hello, My apologies if this is elementary, but is the Hosmer-Lemeshow
> test applicable when I run a binary logistic regression with about
> half
> of the explanatory variables being dichotomous? And if not, how might
> I
> test for model fit in SPSS? Thanks in advance.
>

Yes the Hosmer-Lemeshow test is also applicable for binary logistic
regression.

Hosmer and Lemeshow's Goodness of Fit Test tests the null hypothesis
that the data are generated by the model fitted by the researcher. The
test divides subjects into deciles based on predicted probabilities,
and then computes a chi-square from observed and expected frequencies.
Then a probability (p) value is computed from the chi-square
distribution with 8 degrees of freedom to test the fit of the logistic
model. If the Hosmer and Lemeshow Goodness-of-Fit test statistic is .05
or less, we accept the null hypothesis that there is no difference
between the observed and model-predicted values of the dependent. (This
means the model predicts values significantly different from what they
ought to be, which is the observed values).  If the H-L goodness-of-fit
test statistic is greater than .05, as we want for well-fitting models,
we fail to reject the null hypothesis that there is no difference,
implying that the model's estimates fit the data at an acceptable
level.

Hope this helps,

Debarchana
Department of Geography
Kansas State University