Organize categorical data in two-way tables, compute row and column totals, express counts as relative frequencies, and argue which group shows a stronger pattern without misleading raw counts.
What you’ll learn
Compare row percents to test for an association: similar percents across rows mean the variables are roughly independent.
Two-way tables count joint outcomes for two categorical variables.
Marginal totals sum rows or columns; the grand total counts every case once.
Relative frequencies express "out of this row (or column), what fraction?" for fair comparisons.
Raw cell counts can mislead when group sizes differ; compare rates when the story asks about preference within a group.
Tables complement scatter plots: categories versus paired measurements.