2.3:
Construction of Frequency Distribution
Consider the participants running in a marathon. Suppose one wonders how the number of participants varies with age. In order to find out, the data are summarized using a frequency distribution table, which is constructed using six steps.
First, select the number of classes, anywhere between 5 and 20, depending on the data density. Here, let the number of classes be five.
Subtract the smallest from the largest number to determine the range. Dividing this range by the number of classes yields the class width—the range of values per class, which is rounded up for convenience.
The minimum value of the given data is called the first lower-class limit.
To this value, add the class width to determine the second lower-class limit. Similarly, calculate the subsequent lower-class limits.
Next, subtract one from the second lower-class limit to calculate the first upper-class limit. Likewise, calculate the remaining upper-class limits.
In a second column, place tally marks for the participants under each class. The sum of all tally marks gives the frequency of each class.
2.3:
Construction of Frequency Distribution
A frequency distribution table can be constructed using the steps given below.
First, make a table with two columns—one with the title of the data that needs to be organized, and the other column for frequency. [Draw a third column for tally marks if needed]. Then, take a look at the items given in the data set and decide if an ungrouped frequency distribution table or a grouped frequency distribution table would be more suitable. If there are large sets of different values, then it is best to construct a grouped frequency distribution table. Now, write the data set values in the first column. Count the number of times each item repeats itself in the collected data. In other words, find the frequency of each item by counting, followed by writing the frequency in the second column corresponding to each item. Finally, write the total frequency in the last row of the table.