r - 以 n 为分母的 var、sd、cor 函数

Question

var, sd,cor函数{stats}用作n-1分母（其中n观察数）。出于好奇，是否有等效的函数n用作分母？

Answer 1

尝试这个：

library(RH2) # needs Java
library(sqldf)

n <- length(BOD$demand)

sd(BOD$demand)
sqrt((n-1)/n) * sd(BOD$demand)
sqldf("select stddev_samp(demand) as samp, stddev_pop(demand) as pop from BOD")

var(BOD$demand)
(n-1)/n * var(BOD$demand)
sqldf("select var_samp(demand) as samp, var_pop(demand) as pop from BOD")