Primer 2

data()
data(package = .packages(all.available = TRUE))

podatki <- force(USArrests)

library(psych)
podatki <- force(sat.act)

#Primerjava doseženih točk ACT

summary(podatki$ACT)

##    Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
##    3.00   25.00   29.00   28.55   32.00   36.00

#Spremenimo, da je spol prikazan z M in F in ne z številom 1 in 2

podatki$Spol <- factor(podatki$gender,
                       levels = c(1, 2),
                       labels = c("M", "F"))

library(psych)
describeBy(podatki$ACT, podatki$Spol)

## 
##  Descriptive statistics by group 
## group: M
##    vars   n  mean   sd median trimmed  mad min max range  skew kurtosis   se
## X1    1 247 28.79 5.06     30   29.23 4.45   3  36    33 -1.06     1.89 0.32
## ------------------------------------------------------------ 
## group: F
##    vars   n  mean   sd median trimmed  mad min max range  skew kurtosis   se
## X1    1 453 28.42 4.69     29   28.63 4.45  15  36    21 -0.39    -0.42 0.22