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.
Este exercício faz parte do curso
Multivariate Probability Distributions in R
Instruções do exercício
- 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.
Exercício interativo prático
Experimente este exercício completando este código de exemplo.
# 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)