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help for ^logpred^
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Logistic regression probabilities  (Joanne M. Garrett  05/08/98)
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   ^logpred^ yvar xvar [^if^ exp]^,^ [^f^rom^(^#^) t^o^(^#^) i^nc^(^#^) cl^ass^(^classvar^)^
                      ^p^oly^(^#^) adj^ust^(^covlist^) m^odel ^gr^aph ^nol^ist
                      ^l^evel^(^#^)^ graph_options]
 

^logpred^ calculates and prints probabilities and 95% confidence intervals from
   logistic regression estimates for a continuous X variable, adjusted for
   covariates.  Default prints probabilities and confidence intervals; model
   estimates and graph can be shown. Optionally a quadratic or a quadratic and
   cubic term can be added to the model. An interaction between X and a nominal
   variable can be estimated and graphed. Dummy variables are created for the
   nominal variable with the lowest category defaulting to the reference group.

 
Variables and options required
------------------------------

    yvar -- dependent variable  (dichotomous  0,1)
    xvar -- continuous independent variable (interval or ordinal)
    ^f^rom^(^#^)^ -- bottom value for xvar
    ^t^o^(^#^)^ -- top value for xvar
    ^i^nc^(^#^)^ -- increment size between bottom and top values (defaults to 1)

        
Options allowed 
---------------

    ^cl^ass^(^classvar^)^ -- nominal variable for a xvar by classvar interaction
    ^p^oly^(^2 or 3^)^ -- polynomial terms added: 2=quadratic 3=quadratic and cubic
                       (will not work with the class option)
    ^adj^ust^(^covlist^)^ -- any covariates (if none specified, unadjusted
                       probabilities reported); Covariates set to their mean,
                       based on observations used in the analysis, or can be
                       set to user specified values (e.g., age=50 gender=1)
    ^m^odel -- displays the logistic regression table  
    ^gr^aph -- displays graph of probabilities and 95% confidence intervals; if
             class is requested, confidence intervals are not displayed
    ^nol^ist -- does not print list of probabilites and 95% CIs
    ^l^evel^(^#^)^ -- specifies the confidence level, in percent, for calculation
                    of confidence intervals (default=95%)
    

Examples
--------

 . ^logpred died age, from(20) to(80) inc(5) adj(sys hra) model^

        Calculates the probability of dying for 5 year increments of age
        from 20 years to 80 years (i.e., age=20,25,30,...,80) adjusted
        for systolic blood pressure and heart rate; displays model and
	probabilites but does not display graph


 . ^logpred died sys, f(60) t(300) i(20) adj(age hra) graph ylab xlab^

        Calculates the probability of dying for systolic blood pressure
        readings from 60 to 300 in 20 mm/hg increments, adjusted for age
        and heart rate; displays graph and list of probabilites

 . ^logpred died sys, f(60) t(300) i(20) adj(age hra) class(race) graph^

        Calculates the probability of dying for systolic blood pressure
        readings from 60 to 300 in 20 mm/hg increments, adjusted for age
        and heart rate, by categories of race; displays a likelihood ratio
        test for interaction; graphs the results


 . ^logpred died age, f(40) t(80) poly(3) adj(sys=180) graph xlab ylab nolist^

	Calculates the probability of dying for 1 year increments of age;
	terms for age-squared and age-cubed included in model using the
        poly(3) option; also adjusted for systolic blood pressure of 180;
        displays graph; does not list probabilities and CIs
