varians2.R

Simpan <- read.csv("varians.csv", header = TRUE, sep = ",") #membaca data
Simpan

##    Nilai Kelas
## 1     70     1
## 2     80     1
## 3     87     1
## 4     77     1
## 5     80     1
## 6     80     2
## 7     85     2
## 8     70     2
## 9     77     2
## 10    85     2
## 11    60     2
## 12    80     2
## 13    70     3
## 14    87     3
## 15    90     3
## 16    77     3
## 17    76     3
## 18    87     3

library(doBy)
summaryBy(Nilai ~ Kelas, data = Simpan, FUN = function(x)
{ c(ratarata = mean(x), varians = var(x), jumlah = sum(x) ) } )

##   Kelas Nilai.ratarata Nilai.varians Nilai.jumlah
## 1     1       78.80000      37.70000          394
## 2     2       76.71429      80.57143          537
## 3     3       81.16667      62.96667          487