Organizing Data

A frequency distribution is a way to organize data to make it easier to comprehend.
To construct a frequency distribution
- Create a number of equal sized non-overlapping classes
- Each piece of data should fall within exactly one class.
Do problem 10, page 848
We can group data into larger classes.
The class width is the number of index values that belong to the class.
The lower class limits are the starting numbers for each class.
The upper class limits are the ending numbers for each class.
The modal class is the class with the greatest frequency.
The midpoint of a class or class mark is found averaging the lower and upper class limits.
Do Exercise 12, page 848
- The class width is 9 (80, 81, 82, ... 88)
- The lower class limits are 80, 80+9, 80+2*9, ... (until 135 is covered)
- The upper class limits are 88, 88+9, 88+2*9, ...
- The classes are 80 to 88, 89 to 97, 98 to 106, 107 to 115, 116 to 124, 125 to 133, 134 to 143

Presenting Data