x <- 1:30 
y <- seq(1, 300, 10) + rnorm(30) 
y[5] <- y[5] + 30
y[10] <- y[10] + 9
y[25] <- y[25] - 43
fit <- lm(y ~ x)
plot(fit)

y[5] <- y[5] -5
y[10] <- y[10] + 19
y[25] <- y[25] - 72
fit <- lm(y ~ x)
plot(fit)

y[5] <- y[5] + 3
y[10] <- y[10] + 88888
y[25] <- y[25] + 45
fit <- lm(y ~ x)
plot(fit)

y[5] <- y[5] + 12
y[10] <- y[10] + 4
y[25] <- y[25] - 33
fit <- lm(y ~ x)
plot(fit)

y[5] <- y[5] + 7
y[10] <- y[10] + 9
y[25] <- y[25] - 666
fit <- lm(y ~ x)
plot(fit)