A tabulation of the number of occurrences of each score value. An organized tabulation of scores or categories and the number of times they appear in a given population or sample.
The proportion of observations in the distribution at that score value. The number of occurrences of a particular score value in relationship to the total score value.
Relative Frequency Distribution
A listing of the relative frequencies of each score value.
Cumulative Frequency Distribution
A tabulation of the frequency of all measurements at or smaller than a given score value. Used to help calculate percentiles.
Cumulative Relative Frequency Distribution
A tabulation of the relative frequencies of all measurements at or below a given score value. This is used to directly calculate percentile ranks.
A range of score values. A group of score values that is used to help summarize data that contains many different score values.
Grouped Frequency Distribution
A tabulation of the number of measurements in each class interval or the number of occurrences of scores that fall in each class interval.
x-axis or the horizontal line. Often marked in units of the variable being measured.
y-axis or vertical line. Often marked in units of frequency or relative frequency.
Relative Frequency Histogram
A type of frequency distribution graph that uses the heights of bars to represent relative frequencies of score values or class intervals.
A type of variable in which no values can exist between two adjacent scores or values.
A type of variable in which an infinite number of values can exist between any two scores.
A type of distribution where if it is divided in half, the two halves are mirror images of each other.
Positively skewed distribution
A type of distribution in which the tail of the graph points towards the right hand side or the side with the higher scores.
Negatively skewed distributions
A type of distribution in which the tail of the graph points to the left hand side or the side with the lower values of a score.
Unimodal, Bimodal, Multimodal Distributions
Distribution with one peak or mode. Distribution with two peaks or modes. Distribution with more than two peaks or modes.
Central Tendency of a Distribution
A score value near the center of the distribution; it is supposed to be a typical or representative score value. Often measured as the mean, median, or mode.
The degree to which the measurements in a distribution differ from one another. A measurement of how clustered or scattered the scores are in a given distribution.
The percent of measurements in the distributions below that score value.
The score value with P% of the measurements in the distribution. Not sure if this refers to the actual score or the percentage still.
Ch. 2: Frequency Distributions and Percentiles