Frequency Distribution

Systematic representation of data, arranged so that the observed frequency of occurrence of data falling within certain ranges, classes, or categories, is shown.

When data is presented in a frequency distribution, the objective is to show the number of times a particular value or range of values occurs. Common forms of presentation of frequency distribution include the frequency polygon, the bar graph, and the frequency curve, which associate a number (the frequency) with each range, class, or category of data. A grouped frequency distribution is a kind of frequency distribution in which groups of ranges, classes, or categories are presented. Grouped frequency distributions are generally used when the number of different ranges, classes, or categories is large. A cumulative frequency distribution is a representation in which each successive division includes all of the items in previous divisions (so that, for example, the last division includes all of the data in the entire distribution). A probability distribution is similar to a frequency distribution, except that in a probability distribution the observed probability of occurrence is associated with each range, class, or category. The sum of the probabilities in a probability distribution is one, while the sum of the frequencies in a frequency distribution is the total number of data items.