What does a standard deviation of 15 points indicate in cognitive assessments?

A standard deviation of 15 points in cognitive assessments indicates the degree of variation or dispersion of scores around the average score, also known as the mean. In the context of cognitive assessments, such as IQ tests, the standard deviation helps to understand how individual scores relate to the average score of the population being assessed.

For example, if the average IQ score is 100, a standard deviation of 15 points means that approximately 68% of the population will score between 85 and 115 (one standard deviation above and below the mean). This measurement allows for a better understanding of how typical or atypical a given score is within the context of the entire population.

In contrast, the other options reflect different concepts related to test scores. Consistency in test scores refers to reliability rather than standard deviation. Low variation in test results suggests little difference across scores, which contradicts the meaning of a standard deviation of 15 points that indicates variability. Absolute accuracy in measurement pertains to the precision of the scores, which is not what standard deviation quantifies. Therefore, the understanding of standard deviation as a representation of differences around the average score is essential in interpreting cognitive assessment results.