R: Examples for 'stats::update'

### ** Examples

oldcon <- options(contrasts = c("contr.treatment", "contr.poly"))
## Annette Dobson (1990) "An Introduction to Generalized Linear Models".
## Page 9: Plant Weight Data.
ctl <- c(4.17,5.58,5.18,6.11,4.50,4.61,5.17,4.53,5.33,5.14)
trt <- c(4.81,4.17,4.41,3.59,5.87,3.83,6.03,4.89,4.32,4.69)
group <- gl(2, 10, 20, labels = c("Ctl", "Trt"))
weight <- c(ctl, trt)
lm.D9 <- lm(weight ~ group)
lm.D9

Call:
lm(formula = weight ~ group)

Coefficients:
(Intercept)     groupTrt  
      5.032       -0.371

summary(lm.D90 <- update(lm.D9, . ~ . - 1))

Call:
lm(formula = weight ~ group - 1)

Residuals:
    Min      1Q  Median      3Q     Max 
-1.0710 -0.4938  0.0685  0.2462  1.3690 

Coefficients:
         Estimate Std. Error t value Pr(>|t|)    
groupCtl   5.0320     0.2202   22.85 9.55e-15 ***
groupTrt   4.6610     0.2202   21.16 3.62e-14 ***
---
Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1

Residual standard error: 0.6964 on 18 degrees of freedom
Multiple R-squared:  0.9818,	Adjusted R-squared:  0.9798 
F-statistic: 485.1 on 2 and 18 DF,  p-value: < 2.2e-16

options(contrasts = c("contr.helmert", "contr.poly"))
update(lm.D9)

Call:
lm(formula = weight ~ group)

Coefficients:
(Intercept)       group1  
     4.8465      -0.1855

getCall(lm.D90)  # "through the origin"

lm(formula = weight ~ group - 1)

options(oldcon)

Examples for 'stats::update'

Update and Re-fit a Model Call