Measures of Central Tendency Chapter 4 Measures of Central Tendency

Measures of Central Tendency Mean, Median and Mode Describe the middle or central characteristics of the data In a normal distribution the mean, median and mode are the near the same score

Mode Found by inspection (no formula) Disadvantages of the mode: Terminal statistic (does yield a number that can be used for further calculations) Completely disregards the extreme scores

If N is even report the higher score as the median Median (middle score) In a skewed distribution the median is a better measure of central tendency than the mean. If N is even report the higher score as the median

The Mean The mean includes all data points. Can be used for further calculations Is sensitive to OUTLIERS Outliers: Usually more than 3 SDs above or below the mean.

Relationships Among Mode, Median and Mean In a normal distribution all fall at or near the save value Use the mode only for rough estimate Use the median For ordinal data If the distribution is skewed Use the mean For ration data, with normal distribution If further calculations are needed

Mean From a Frequency Distribution