- The three most important measures of central tendency are: (1) Mean (average score); (2) Mode (most common score); and (3) Median (middle score).
- If the distribution is fairly symmetric, the median and mean are (approximately) equal.
- If the distribution is skewed, the mean of the distribution is "pulled towards" these extremes. Thus, if the distribution is positively skewed, the mean is to the right of the median. If the distribution is negatively skewed, the mean is to the left of the median (the median is more robust to extreme values).