x <- 1:30 
y <- seq(1, 300, 10) + rnorm(30)
y[2] <- y[2] + 21
y[4] <- y[4] + 7
y[6] <- y[6] - 1
fit <- lm(y ~ x)
plot(fit)

x <- 1:30 
y <- seq(1, 300, 10) + rnorm(30)
y[16] <- y[16] + 1
y[12] <- y[12] + 51
y[5] <- y[5] - 88
fit <- lm(y ~ x)
plot(fit)

x <- 1:30 
y <- seq(1, 300, 10) + rnorm(30)
y[16] <- y[16] + 1
y[12] <- y[12] + 15
y[5] <- y[5] - 8
fit <- lm(y ~ x)
plot(fit)

x <- 1:30 
y <- seq(1, 300, 10) + rnorm(30)
y[5] <- y[5] + 55
y[10] <- y[10] + 12
y[25] <- y[25] - 76
fit <- lm(y ~ x)
plot(fit)

x <- 1:30 
y <- seq(1, 300, 10) + rnorm(30)
y[5] <- y[5] + 88
y[10] <- y[10] + 80
y[25] <- y[25] - 44
fit <- lm(y ~ x)
plot(fit)