A tabular arrangement of data that shows the frequency of occurrence of the different values of the variables.

It is use to rank the disorganized data from highest to lowest or vice versa.

It is use to organize tabulation of the no. of the individual scores located in each category X for score and f for the frequency.

It is use to summarizes the distribution of the values.

Class interval - the range of such class of data is called the Class Interval.

Class limit - The lower and upper limits of a class interval are known as Class Limits.

Class boundaries – the values between the upper limit of one interval and the lower limit of the next interval.

Class mark - Midpoint of a class interval. Class frequency - Refers to the number of

observation belonging to a class interval. Class size - the total number of

observations on which class interval is formed.

Problem A: Using following data, construct a frequency distribution table of weight of 50 boys. Use 8 class intervals of equal size and also find class boundaries and mid class. 125, 108, 119, 115, 129, 140, 137, 130, 129, 124, 111, 100, 127, 130, 150, 96, 141, 122, 122, 136, 92, 124, 139, 109, 105, 114, 131, 124, 136, 132, 151, 127, 125, 123, 119, 124, 134, 129, 104, 102, 125, 148, 143, 124, 123, 101, 147, 100, 126, 131.

Ascending Order:92, 96, 100, 100, 101, 102, 104, 105, 108, 109, 111, 114, 115, 119, 119, 122, 122, 123, 123, 124, 124, 124, 124, 124, 125, 125, 125, 126, 127, 127, 129, 129, 129, 130, 130, 131, 131, 132, 134, 136, 136, 137, 139, 140, 141, 143, 147, 148, 150, 151.

Range = Largest Observation - Smallest Observation

Here, Largest Observation = 151 Smallest Observation = 92 

Range = 151 - 92 = 59

From the problem we use 8 class intervals of equal size and the range for the given data is 59, so in order to find the size of class interval.

The formula will be;Size of class interval = Range

Total no. of class intervals 

Size of class interval = 59/8 = 7.375 = 8 (note: in case the fraction appears, the next higher whole number is usually taken as the size of the class interval).

Weight Tally frequency

92-98 II 2

99-106 IIIII I 6

107-114 IIII 4

115-122 IIIII 5

123-130 IIIII IIIII IIIII III 18

131-138 IIIII II 7

139-146 IIII 4

147-154 IIII 4

Prepared by : Ms. Ma. Teresa B. Berondo

Prof.: Maria Fe Gueta Inferential Statistic