Measures of Central Tendency:Although, frequency distributions serve useful purposes, there are many situations that require other types of data summarisation. What we need in many instances is the ability to summarise the data by means of just a few descriptive measures. Descriptive measures may be computed from the data of a sample or the data of a population. To distinguish between them, we have the following definitions.
- A descriptive measure computed from the data of a sample is called a statistic.
- A descriptive measure computed from the data of a population is called a parameter.
Measures of central tendency convey information regarding the average value of a set of values. The word ‘average’ can be defined in different ways. Following are the five measures of central tendency that are in common use:
- Arithmetic Mean
- Median
- Mode
- Geometric Mean and
- Harmonic Mean
Arithmetic mean of a set of observations is their sum divided by the number of observations. In case of frequency distribution, formula will be different. In case of continuous frequency distribution, use of mid-points of the classes is considered.
