update() is bad

update.md

data <- mtcars
m <- lm(mpg ~ wt, data)

data <- mtcars[-c(1:10), ]
m_update <- update(m, . ~ . + disp)

nobs(m)
#> [1] 32

nobs(m_update)
#> [1] 22

# but i didn't want to change the data. all i updated 
# was the formula

^{Created on 2024-04-15 with reprex v2.1.0}