Chapter Terminology
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Chapter Two Terms

Chapter Two Terminology
Frequency Table - A table that lists classes or categories of values along with frequencies or counts of the number of values that fall into each class.

Histogram - A bar graph in which the horizontal axis represents classes and the vertical axis represents the frequency counts.

Scatter Diagram - A plot of paired (x , y) data values with a horizontal x-axis and a vertical y-axis. The pattern of the plot helps to determine whether there is some relationship between the two variables.

Mean - The most common measure of central tendency, the mean is obtained by adding together all the data values in a set and dividing the total by the number of data values in the set.

Median - The middle value when the original set of values are ordered from smallest to largest.

Mode - The value that occurs most often in a data set. There may be no mode in a data set (no values are repeated) of more than one mode (two or more values that occur with the same greatest frequency).

Midrange - The average of the highest and lowest data values in a set.

Standard Deviation - Measure of variation that tells us how far away from the mean the data values are.

Range - Measure of variation that is found by taking the difference between the highest and lowest values in a data set.

Standard Score or Z-score - Measure of position that tells how many standard deviations away from the mean a given value is. This measure will be used extensively throughout this course.

Usual and Unusual Values - A value is considered to be 'usual' or ordinary if it is within two standard deviations of the mean. In other words, the Z-score of a 'usual' value is between -2.00 and 2.00. A data value with a Z-score less than -2.00 or more than 2.00 is considered to be an 'unusual' occurrence.