| A | B |
|---|
| To describe a distribution of scores, you need... | an index of variability and a measure of central tendency. |
| The range is... | the distance between the highest and the lowest scores in the distribution. |
| To calculate the range... | subtract the lowest score from the higest score and add 1. |
| The range is mostly used... | for descriptive purposes and not as an index of variability. |
| The deviation score is... | the distance of the raw score from the mean, (the score minus the mean.) |
| The variance is... | the mean-squared deviation. |
| To calculate the variance for a population... | square each deviation score, add all squared deviations, and divide their sum by the number of scores. |
| To calculate the variance for a sample... | square each deviation score, add all squared deviations, and divide their sum by the number of scores minus 1. |
| The standard deviation is... | the square root of the variance. |
| The standard deviation indicates... | the average (mean) distance of scores from the mean. |
| There are two methods to calculate the variance and the SD: | the deviation score and the raw score |
| The variance is not commonly used when describing... | a distribution of scores. |
| Standard deviation is used extensively to describe... | a distribution of scores and reporting test results. |
| In heterogeneous groups, the range, variance, and SD are... | higher. |
| In homogeneous groups, the range, variance, and SD are... | lower. |
| Variance and SD are higher on tests that are... | longer (with more items.) |
| Variance and SD are lower on tests that are... | shorter (with fewer items.) |
