Two-Way Tables Flashcards

All 5 cards in this deck

What is a two-way table?

A table that shows the frequencies for two different categories at the same time, with row totals, column totals and a grand total.

What are the steps to complete a two-way table?

e.g. 20 people: 12 are adults, 8 are children; 5 of the adults chose tea, 9 people chose tea altogether

1. Write in the values given: adults–tea $= 5$.
2. Subtract from a row or column total to fill a gap: adults–coffee $= 12 - 5 = 7$.
3. Use the other totals for the rest, then check every row and column adds up: children–tea $= 9 - 5 = 4$.

One person is chosen at random from everyone in a two-way table. How do you find the probability that they are in a particular cell?

Divide that cell's frequency by the grand total.

e.g. cell of $7$ out of $20$ people gives $\frac{7}{20}$.

True or false? In a completed two-way table, the row totals add up to the same number as the column totals.

True. Both add up to the grand total.

True or false? The numbers inside a two-way table are probabilities, so they should add up to $1$.

False. They are frequencies, and they add up to the grand total.