Joint and Marginal Relative Frequencies
Grade 8 math students learn about joint and marginal relative frequencies in two-way tables, always dividing by the grand total. Joint relative frequency = joint frequency / grand total, while marginal relative frequency = marginal total / grand total. This converts raw counts into percentages for easier comparison. Covered in Big Ideas Math, Course 3, Chapter 9: Data Analysis and Displays.
Key Concepts
Property Raw counts are hard to compare, so we often convert them into percentages called relative frequencies .
To find a Joint or Marginal Relative Frequency, you ALWAYS divide by the Grand Total (the total number of all people surveyed, located in the bottom right corner).
Joint Relative Frequency = $\frac{\text{Joint Frequency}}{\text{Grand Total}}$ Marginal Relative Frequency = $\frac{\text{Marginal Frequency}}{\text{Grand Total}}$.
Common Questions
What is a joint relative frequency?
A joint relative frequency is calculated by dividing a specific cell count (joint frequency) by the grand total of all people surveyed. It tells what percentage of the entire group fits both categories.
What is a marginal relative frequency?
A marginal relative frequency is calculated by dividing a row or column total (marginal frequency) by the grand total. It tells what percentage of the entire group fits one category, regardless of the other.
What is the grand total in a two-way table?
The grand total is the total number of all subjects surveyed, usually found in the bottom-right corner of a two-way table. Both joint and marginal relative frequencies are divided by the grand total.
Which textbook covers joint and marginal relative frequencies for Grade 8?
This topic is in Big Ideas Math, Course 3, Chapter 9: Data Analysis and Displays.
What grade level covers two-way tables and relative frequencies?
Joint and marginal relative frequencies are typically covered in Grade 8 math statistics.