以 n 作为分母的 var、sd、cor 函数

Question

var、sd、cor函数用作分母（其中观测值{stats}的数量）。出于好奇，是否有等效函数用作分母？n-1nn

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")