[R] How to intepret a factor response model?

From: Maciej Bliziński <m.blizinski_at_wsisiz.edu.pl>
Date: Wed 04 May 2005 - 17:23:17 EST


Hello,

I'd like to create a model with a factor-type response variable. This is an example:

> mydata <- data.frame(factor_var = as.factor(c(rep('one', 100), rep('two', 100), rep('three', 100))), real_var = c(rnorm(150), rnorm(150) + 5))
> summary(mydata)

 factor_var real_var

 one  :100   Min.   :-2.742877  
 three:100   1st Qu.:-0.009493  
 two  :100   Median : 2.361669  
             Mean   : 2.490411  
             3rd Qu.: 4.822394  
             Max.   : 6.924588  

> mymodel = glm(factor_var ~ real_var, family = 'binomial', data = mydata)
> summary(mymodel)

Call:
glm(formula = factor_var ~ real_var, family = "binomial", data = mydata)

Deviance Residuals:

    Min 1Q Median 3Q Max -1.7442 -0.6774 0.1849 0.3133 2.1187

Coefficients:

            Estimate Std. Error z value Pr(>|z|)    
(Intercept)  -0.6798     0.1882  -3.613 0.000303 ***
real_var      0.8971     0.1066   8.417  < 2e-16 ***
---
Signif. codes:  0 `***' 0.001 `**' 0.01 `*' 0.05 `.' 0.1 ` ' 1 

(Dispersion parameter for binomial family taken to be 1)

    Null deviance: 381.91  on 299  degrees of freedom
Residual deviance: 213.31  on 298  degrees of freedom
AIC: 217.31

Number of Fisher Scoring iterations: 6

---------------------------------------------------------------------

For models with real-type response variable it's easy to figure out,
what's the equation for the response variable (in the model). But here
- how do I interpret the model?

-- 
God made the world in six days, and was arrested on the seventh.

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Received on Wed May 04 17:27:36 2005

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