Open-ended class
Also called: Open-ended distribution · Topic: Economic Data: Census, NSS, Surveys and Statistical Tools · NCERT: Class 11, Ch 3 "Organisation of Data"; Class 11, Ch 5 "Measures of Central Tendency"
Meaning
An open-ended class is missing one of its limits. The first class has no lower limit ("less than 10") or the last class has no upper limit ("70 and over"). Such classes are generally undesirable in a frequency table. Without both limits, the class has no class mark (midpoint). So the arithmetic mean cannot be calculated, because every value in a class is represented by its class mark. The median and mode can still be found, because they depend on position and on the densest class, not on the extreme values.
Example
An age table might end with "70 and over". We cannot tell whether this class holds people aged 71 or 95. So no class mark can be fixed, and the mean age cannot be worked out.
Don't confuse with
- Open-ended question: this is a survey question that lets people answer freely in their own words. It has nothing to do with class limits.
Related concepts
- Raw data
- Classification
- Chronological classification
- Spatial classification
- Qualitative classification
- Quantitative classification
- Attribute
- Continuous variable
- Discrete variable
- Frequency