Explain the 'exclusive' and 'inclusive' methods used in classification of data.
The Inclusive Method is a technique of classification where both the upper and lower class limits are included in the frequency of that class. For example, in the class interval 0-10, both values 0 and 10 are included in this class. This method is often used for continuous variables. An example of inclusive class intervals is: 0-10, 11-20, 21-30, and so on up to 91-100. The Exclusive Method is a technique where either the upper class limit or the lower class limit is excluded from the frequency of that class. For example, in exclusive class intervals like 0-10, 10-20, 20-30, the value 10 would be excluded from the first class and included in the second class (upper limit excluded). Alternatively, it could be placed in the first class (lower limit excluded). This method ensures continuity between class intervals.
Explanation
The textbook clearly distinguishes between the two methods. In the Inclusive Method, values equal to both the lower and upper limits are included in the same class (e.g., 0-10 includes both 0 and 10). In the Exclusive Method, either the upper or lower limit is excluded - commonly the upper limit is excluded, meaning a value of 10 goes into class 10-20, not 0-10. The context provides examples: inclusive form (0-10, 11-20, 21-30...) vs exclusive form (0-10, 10-20, 20-30...). Both methods can be used for discrete variables, while inclusive intervals are often used for continuous variables.