3.2 The Mean

• the sum of the scores divided by the number of scores

• must be between the range of scores•mean for a population is identified by mu (μ)

• mean for a sample is identified by M or x-bar

• subscripts are used if there is more than one sample

3.3 The Median

• midpoint of the list•no symbols or special notation

3.4 The Mode

• score or category with the greatest frequency

• no symbols or special notation

• can be found for nominal values

• bimodal (two modes) or multimodal (many modes) is possible

3.5 Central Tendency and the Shape of Distribution

Symmetrical Distributions

• The right-hand side of the graph is a mirror of the left-hand side

• median and mean are at the center of a perfectly symmetrical distribution (therefore having the same value)

Skewed Distributions

• strong tendency for the mean, median, and mode to be placed in different positions