### Chapter 1. Descriptive Statistics: Frequency Distributions

### Frequency Distributions

The primary purpose of descriptive statistics is to organize and summarize large amounts of raw data into a more comprehensible form. One useful way of organizing a dataset is with the help of a *frequency distribution*.

Frequency distribution

A **frequency distribution **organizes a sample by ordering the observations from lowest to highest score and grouping together all observations with the same score.

A frequency distribution can be presented either as a table or as a graph. In each case, the frequency distribution is made up out of two components: the *categories* of the measurement scale used and the *frequency *of observations in each category.

There are three important properties of a frequency distribution:

- Centrality
- Variability
- Shape

*Centrality* refers to what a typical or average score looks like. *Variability* relates to whether the scores are clustered together or spread out evenly. The *shape* of a distribution is related to the degree to which a distribution is either symmetrical or skewed.

Lastly, a frequency distribution can be used to determine the *location* of a specific observation within the distribution.

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