偶然看到YIHUI大神提供的 这个数据 ,试着拟合了一下,感觉好像更符合NB啊。 代码如下: (借用了评论1里的画图脚本) len <- c(20,20,13,15,2,11,31,10,12,20,13,56,7,13,19,46,16,19,14,9,20,10,22,13,2,43,11,15,20,14,26,10,19,33,15,15,65,7,16,18,10,32,14,17,14,24,19,60,13,17,27,7,12,7,11,70,50,8,13,8,15,2,20,27,39,7,7,26,21,19,22,8,26,42,8,17,37,17,5,14,21,8,28,18,69,12,23,12,17,14,17,8,20,31,36,25,20,6,6,11) mean(len) sd(len) hist(len, 20) ll.pois <- function(p) { mu <- p[1] ll <- sum(dpois(len, lambda = mu, log = T)) -ll } ll.norm <- function(p) { mu <- p[1] sigma2 <- p[2] ll <- sum(dnorm(len, mean = mu, sd = sigma2, log = T)) -ll } ll.nb <- function(p) { mu <- p[1] theta <- p[2] ll <- sum(dnbinom(len, mu=mu, size = theta, log=T)) -ll } out.pois <- nlm(ll.pois, 2) out.norm <- nlm(ll.norm, c(2,1)) out.nb <- n...