Standard deviation

The standard deviation is a measure of how far the scores are spread around the mean.

High standard deviation indicates that scores have greater variety and spread than a low standard deviation.

In Oxford Score tests, the mean (or the average score) and the standard deviation are dynamically computed from all the tests done in the past for each topic. They are given as a percentage, so, for example, the average score for a particular test could be 62% and the standard deviation 6.1%, which would indicate that most candidates are scoring around the average mark. Another test could have the average score of 52% and the standard deviation of 36.1%, which would indicate that there is a relatively large variation in the candidate scores.

The mean is shown on the graph as the vertical line in the middle of the blue area. One standard deviation from the mean in either direction on the horizontal axis (the blue "A" area on the graph) accounts for 68.3% of the scores. Two standard deviations from the mean (the blue and red "B" areas) account for 95.4% of the scores. Three standard deviations (the blue, red and green "C" areas) account for 99.7% of the scores.

For more information on standard deviation see Wikipedia