# Scores types explained

**Z-Score**

A z-score indicates how many standard deviations a score is from the mean. A z-score can be calculated thus: z = (X - μ) / σ where z is the z-score, X is the score, μ is the population mean, and σ is the standard deviation. A positive z score is an above average score, 0 is an average score and a negative z-score is below average. A z-score of -1.5 or below on a BICAMS test is suggestive of cognitive impairment.

**Scaled Score**

A scaled score is calculated by converting raw scores onto a common, consistent scale, so that scores on different tests are comparable. The scale is divided into stanines (scaled scores 1-9).