September 4, 2014

Uni, bi, multi…

  • Univariate data analysis - distribution of single variable

  • Bivariate data analysis - relationship between two variables

  • Multivariate data analysis - relationship between many variables at once, usually focusing on the relationship between two while conditioning for others

Types of variables

  • Numerical variables can be classified as continuous or discrete based on whether or not the variable can take on an infinite number of values or only non-negative whole numbers, respectively.

  • If the variable is categorical, we can determine if it is ordinal based on whether or not the levels have a natural ordering.

Describing shapes of numerical distributions

  • shape:
    • skewness: right-skewed, left-skewed, symmetric (skew is to the side of the longer tail)
    • modality: unimodal, bimodal, multimodal, uniform
  • center: mean (mean), median (median), mode (not always useful)
  • spead: range (range), standard deviation (sd), inter-quartile range (IQR)
  • unusal observations

Now put these, and more, to use…

Complete application exercise 2 in teams, and submit on Sakai (one submission per team)