[R] extracting 'Z' value from a glm result

[Chuck Cleland]

summary(model)$coefficients[,3]

or

summary(model)$coefficients[-1,3]

For example:

 > counts <- c(18,17,15,20,10,20,25,13,12)
 >      outcome <- gl(3,1,9)
 >      treatment <- gl(3,3)
 > glm.D93 <- glm(counts ~ outcome + treatment, family=poisson())
 > summary(glm.D93)

Call:
glm(formula = counts ~ outcome + treatment, family = poisson())

Deviance Residuals:
        1         2         3         4         5         6         7
-0.67125   0.96272  -0.16965  -0.21999  -0.95552   1.04939   0.84715
        8         9
-0.09167  -0.96656

Coefficients:
               Estimate Std. Error  z value Pr(>|z|)
(Intercept)  3.045e+00  1.709e-01   17.815   <2e-16 ***
outcome2    -4.543e-01  2.022e-01   -2.247   0.0246 *
outcome3    -2.930e-01  1.927e-01   -1.520   0.1285
treatment2   8.717e-16  2.000e-01 4.36e-15   1.0000
treatment3   4.557e-16  2.000e-01 2.28e-15   1.0000
---
Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1

(Dispersion parameter for poisson family taken to be 1)

     Null deviance: 10.5814  on 8  degrees of freedom
Residual deviance:  5.1291  on 4  degrees of freedom
AIC: 56.761

Number of Fisher Scoring iterations: 4

 >      summary(glm.D93)$coefficients[,3]
   (Intercept)      outcome2      outcome3    treatment2    treatment3
  1.781478e+01 -2.246889e+00 -1.520097e+00  4.358442e-15  2.278668e-15
 >      summary(glm.D93)$coefficients[-1,3]
      outcome2      outcome3    treatment2    treatment3
-2.246889e+00 -1.520097e+00  4.358442e-15  2.278668e-15

Taka Matzmoto wrote:
> Hello R users
> I like to extract z values for x1 and x2. I know how to extract coefficents 
> using model$coef
> but I don't know how to extract z values for each of independent variable. I 
> looked around
> using names(model) but I couldn't find how to extract z values.
> 
> Any help would be appreciated.
> 
> Thanks
> 
> TM
> 
> #########################################################
>> summary(model)
> 
> Call:
> glm(formula = y ~ x1+ x2, family = binomial)
> 
> Deviance Residuals:
>     Min       1Q   Median       3Q      Max
> -2.1397  -1.2357   0.6875   0.8517   1.5743
> 
> Coefficients:
>               Estimate     Std. Error   z value   Pr(>|z|)
> (Intercept) -0.63930    1.13045  -0.566    0.572
> x1              0.69956    0.09459   7.396 1.40e-13 ***
> x2              1.51389    1.13212   1.337    0.181
> ---
> Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
> 
> (Dispersion parameter for binomial family taken to be 1)
> 
>     Null deviance: 1214.9  on 999  degrees of freedom
> Residual deviance: 1149.8  on 997  degrees of freedom
> AIC: 1155.8
> 
> Number of Fisher Scoring iterations: 4
> ############################################################
> 
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-- 
Chuck Cleland, Ph.D.
NDRI, Inc.
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