13/01/13 13:52:12.00
>>730
乱数の分散を変えてみると、理解出来るのでは？
> set.seed(1234); sum(hist(rnorm(500, sd = 2), prob = TRUE)$density)
[1] 1
> set.seed(1234); sum(hist(rnorm(500, sd = 5), prob = TRUE)$density)
[1] 0.2
> set.seed(1234); sum(hist(rnorm(500, sd = .1), prob = TRUE)$density)
[1] 20