Grouped frequency tables
for 8th grade

Grouped frequency tables

Data in frequency tables can be discrete or continuous. Discrete data consists of single values, often whole numbers, and is how most data is initially gathered. If there are many data points to process, it becomes useful to group that data into a set of classes of continuous data. Continuous data can be represented in a "Grouped frequency table". Each class covers the data points within a certain range, and the classes together cover the entire range of all the data points. In grouped frequency tables, it is important that the classes cover the entire range of the given data while not overlapping.

The benefit of grouped frequency tables becomes clear when there are so many raw data points that discrete values would become difficult to process. A limitation of continuous data is that individual data points are lost so that exact calculations of the mode, median or range of the original discrete data points becomes impossible.

In this topic you are asked to compare each grouped frequency table to the raw data that it should represent. Many of the tables have deliberate mistakes that you must identify. You can do so by counting up the data points for each class and comparing them to the given frequencies.

In the first question, the raw discrete data points are:

10, 8, 25, 18, 15, 22, 5 ,9

The grouped frequency table splits the data into classes: 1-10, 11-20, 21-30.

The frequency for the 1-10 class is given as 4. We can look through the data points and confirm that there are indeed 4 values within this range: 10, 8, 5 and 9. So that frequency is correct. Checking the 2 other classes shows us that the table does indeed accurately represent the data, so the answer in this case is "yes, the table does match the data".