Inclusive method
Also called: Inclusive class interval · Topic: Economic Data: Census, NSS, Surveys and Statistical Tools · NCERT: Class 11, Ch 3 "Organisation of Data"; Class 11, Ch 8 "Use of Statistical Tools"
Meaning
In the inclusive method of classification, a class includes values equal to both its lower and its upper limit. So the classes are written 0-10, 11-20, 21-30, and there is a gap between one class and the next. Because of these gaps, the classes are not continuous. A continuous variable needs continuous classes. So before drawing histograms or working out the median and mode, we make an adjustment in class interval. Take half the gap between one class's upper limit and the next class's lower limit. Subtract it from every lower limit and add it to every upper limit.
Example
Suppose the classes are 800-899, 900-999 and so on. The gap is 900 − 899 = 1, and half of it is 0.5. After adjustment, 800-899 becomes 799.5-899.5 and 900-999 becomes 899.5-999.5. Now the classes join up with no gaps.
Don't confuse with
- Exclusive method: here the upper limit belongs to the next class (10-20, 20-30). A value of 20 goes into 20-30, so the classes are already continuous.
Related concepts
- Raw data
- Classification
- Chronological classification
- Spatial classification
- Qualitative classification
- Quantitative classification
- Attribute
- Continuous variable
- Discrete variable
- Frequency