Homework Assignment #8

Problem 1

  1. Load Howell’s craniometric dataset
  2. Get rid of unwanted data. Select only the following columns: ID, Sex, Population, BNL, MDH, EKB, ZOR, BAA, NBA. Filter the dataset to only include individuals from the following populations: BUSHMAN, PERU, NORSE, ZULU. Use this filtered dataset for all remaining questions in this homework.
  3. Calculate the variance / covariance matrix for the 6 numeric variables.

Problem 2

  1. Perform a Principal Components Analysis on the data…make sure to use scale=TRUE to scale your variables!
  2. Which single variable has the strongest loading on PC1?
  3. What is the cumulative proportion of variance explained by PC1 and PC2?
  4. Make a plot of the PC1 scores against PC2 scores. Color code the point based on the population variable.