How to pull out Dispersion parameter in R - r

Question

Call:
glm(formula = Y1 ~ 0 + x1 + x2 + x3 + x4 + x5, family = quasibinomial(link = cauchit))
Deviance Residuals:
Min 1Q Median 3Q Max
-2.5415 0.2132 0.3988 0.6614 1.8426
Coefficients:
Estimate Std. Error t value Pr(>|t|)
x1 -0.7280 0.3509 -2.075 0.03884 *
x2 -0.9108 0.3491 -2.609 0.00951 **
x3 0.2377 0.1592 1.494 0.13629
x4 -0.2106 0.1573 -1.339 0.18151
x5 3.6982 0.8658 4.271 2.57e-05 ***
---
Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1
(Dispersion parameter for quasibinomial family taken to be 0.8782731)
Null deviance: 443.61 on 320 degrees of freedom
Residual deviance: 270.17 on 315 degrees of freedom
AIC: NA
Number of Fisher Scoring iterations: 12
Here is the output from glm in R.
Do you know a way to pull out Dispersion parameter which is 0.8782731 in this case, instead of just copy and paste. Thanks.

Answer 1

You can extract it from the output of summary:
data(iris)
mod <- glm((Petal.Length > 5) ~ Sepal.Width, data=iris)
summary(mod)
#
# Call:
# glm(formula = (Petal.Length > 5) ~ Sepal.Width, data = iris)
#
# Deviance Residuals:
# Min 1Q Median 3Q Max
# -0.3176 -0.2856 -0.2714 0.7073 0.7464
#
# Coefficients:
# Estimate Std. Error t value Pr(>|t|)
# (Intercept) 0.38887 0.26220 1.483 0.140
# Sepal.Width -0.03561 0.08491 -0.419 0.676
#
# (Dispersion parameter for gaussian family taken to be 0.2040818)
#
# Null deviance: 30.240 on 149 degrees of freedom
# Residual deviance: 30.204 on 148 degrees of freedom
# AIC: 191.28
#
# Number of Fisher Scoring iterations: 2
summary(mod)$dispersion
# [1] 0.2040818
The str function in R is often helpful to solve these sorts of questions. For instance, I looked at str(summary(mod)) to answer the question.