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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