1. Measures of Central Tendency
Chapter 4
Measures of Central Tendency

2. 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

3. 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

4. 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

5. 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.

6. 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

8. Mean From a Frequency Distribution