MEGA Elementary Education Multi-Content Practice Test

Which statistical measure would be least effective for understanding the average performance of a small group with extreme scores?

1. Mean

2. Median

3. Mode

4. Range

The correct answer is: Mean

The mean, or average, is calculated by summing all the values in a dataset and dividing by the number of values. In a small group, especially when there are extreme scores or outliers, the mean can be heavily influenced by these outlier values. For example, if the group has scores of 10, 12, 11, and 100, the mean would be skewed significantly higher to reflect the score of 100, which does not accurately represent the general performance of the group. In contrast, the median provides a better measure of central tendency in this scenario. It identifies the middle value when scores are arranged in order, thus it is less sensitive to extreme values. The mode represents the most frequently occurring score and is not as useful for understanding the overall performance in cases with extreme values affecting the distribution. Finally, the range measures the spread of the scores but does not provide insight into the average performance itself. Thus, the mean's vulnerability to outliers makes it the least effective measure for understanding the average performance of a small group with extreme scores.