Chapter Main Points and Learning Objectives
Chapter main points
- The mode, the median, and the mean are measures of central tendency—numbers that describe what is average or typical about the distribution.
- The mode is the category or score with the largest frequency (or percentage) in the distribution. It is often used to describe the most commonly occurring category of a nominal-level variable.
- The median is a measure of central tendency that represents the exact middle of the distribution. It is calculated for variables measured on at least an ordinal level of measurement.
- The mean is typically used to describe central tendency in interval-ratio variables, such as income, age, or education. We obtain the mean by summing all the scores and dividing by the total (N) number of scores.
- In a symmetrical distribution, the frequencies at the right and left tails of the distribution are identical. In skewed distributions, there are either a few extremely high (positive skew) or a few extremely low (negative skew) values.
- Explain the importance of measures of central tendency
- Calculate and interpret the mode, the median, and the mean
- Identify the relative strengths and weaknesses of the three measures
- Determine and explain the shape of the distribution