Perhaps Szklo and Nieto's book can help: Epidemiology. Beyond the
Basics, discusses test for trend (dose reponse) in Appendix B (pp 459-462).
Formula is from Mantel:
Mantel N. Chi square tests with one degree of freedom: etensions of the
Manetel-Haenszel procedure. J Am Stat Assoc. 1963;58: 690-700.
Hope this helps.
Suzy
Young Hee Rho wrote:
>I have encountered many "trend tests" of linearity concerning odds ratios (OR) of a
>categorical variable.
>For example, I am modeling a logistic model Y=b1x1 + b2x2 + b3x3 +b4. x2 is a 5-level
>categorical variable, for example the level of drinking (while Y is the presence/absence of
>hyperuricemia). When the results are displayed, the ORs of the 5 levels are shown and
>the linear trend is shown as a single p value. The individual ORs may not have significance,
>however the overall trend does. It is said that it was tested through regressing the median of
>the levels on the ORs. Otherwise in other cases, there are many trend tests of linearity
>expresed in many papers, however, the actual method is not explained in detail. (It does not
>apear to come from polynomial contrasts of ANOVA nor from categorical trend tests
>(Cochrane-Armitage) since the arformentioned test is from values coming from
>one categorical variable having several estimates. How is this done and how much methods
>exsist on this topic? Are there any useful references?
>** For those who got twice this article, I sent this article again since it did not seem to register on
>Statalist. Many apologies if there was a duplicate delivery.
>
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