Effect of Additional Data and Outliers

Some descriptions of a set of data are called the mean, median, and mode

The mean is the sum of all the items divided by the number of items in the set. Sometimes the mean is also called an average

The median is the middle value when the data are in numerical order, or the mean of the two middle values if there are an even number of items

The mode is the value or values that occur most often. There may be more than one mode for a data set. When all values occur an equal number of times, the data set has no mode

An outlier is a value in a set that is very different from the other values. An outlier significantly affects the mean. The mean may not realistically describe the data set due to the outlier

Sometimes one or two data values can greatly affect the mean, median, or mode. When one of these values is affected like this, you should choose a different value to describe the data set

Some data sets do not contain numbers.  When it does not contain numbers, the only way to describe a data is with the mode