Calculating the mean vector
The first step in analyzing multivariate data is computing the mean vector. The wine dataset consists of several variables. You will calculate the mean vector of the first four numeric variables, Alcohol, Malic, Ash, Alcalinity, which are located in columns 2 through 5. When observations in a dataset have different subgroups, like wine type, it is also helpful to calculate the mean vector by group.
This exercise is part of the course
Multivariate Probability Distributions in R
Exercise instructions
- Calculate the mean of the variables first four numeric variables, which appears in column
2:5using functioncolMeans(). - Calculate the mean of the above variables for each of the wine types, using the
by()function.
Hands-on interactive exercise
Have a go at this exercise by completing this sample code.
# Calculate the mean of the Alcohol, Malic, Ash, and Alcalinity variables
colMeans(wine[___])
# Calculate the mean of the variables by wine type
by(wine[___], wine$___, colMeans)