1. REMEMBER: scatterplot two-way frequency table
Quantitative Data: (numerical data where
arithmetic operations make sense) and
Categorical Data (categories) . . .
You can organize two types of Quantitative Data
into a __________________.
You can organize two types of Categorical Data
into a ____________________________.
scatterplot
two-way frequency table

2. A way to organize TWO categorical variables
Two-Way Frequency Table:
Some suggest shading the table with two colors. If you don’t have two colors, at least do one. Do “joint” one color, and “marginal” another.
Two-way Relative Frequency Table:
A survey was taken of students and what flavor of ice cream they preferred.
FILL IN the marginal frequencies (the totals of the columns and the rows).
A way to organize TWO categorical variables
Create a Relative Frequency Table using PERCENTS.
Displays both the joint relative frequencies and marginal relative frequencies

3. Joint relative frequency:
Marginal relative frequency:
Conditional relative frequency:
Use the two-way relative frequency table to answer the following:
1. What percent of those surveyed preferred vanilla?
2. What percent of those surveyed preferred chocolate?
3. Of those surveyed, what percent were girls?
4. What percent of the girls preferred
something other than vanilla or chocolate?
5. What percent of those who preferred chocolate were boys?
6. What is the conditional probability that
a girl preferred chocolate?
7. What is the conditional probability that a boy
preferred something other than vanilla or chocolate?
Divide frequencies within the “body” of the table by the grand total
Divide row and column totals by the grand total
Divide pieces in the body by the row or column totals, not the grand total.
These questions have “CONDITIONS.”
Be careful! Think!
“OF” is key for the denominator.