mydata <- data.frame("ID" = c(1, 2, 3, 4, 5),
                     "Height" = c(123, 152, 253, 531, 531),
                     "Weight" = c(30, 50, 20, 60, 70))
mean(mydata$Height) #Calculation of mean - height
## [1] 318

On average everyone in the sample has 318cm

summary(mydata[ , -1]) # bitno! [(ovde e za rows), (ovde e za columns)] !
##      Height        Weight  
##  Min.   :123   Min.   :20  
##  1st Qu.:152   1st Qu.:30  
##  Median :253   Median :50  
##  Mean   :318   Mean   :46  
##  3rd Qu.:531   3rd Qu.:60  
##  Max.   :531   Max.   :70
mydata$Gender <- c("F", "F", "M", "M", "M") # creating a variable

Calculate a new variable, called BMI

mydata$BMI <- round(mydata$Height / (mydata$Height/100)^2, 1)