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Converting standardised scores to Percentiles

The following file contains a table displaying corresponding percentile scores (and other standardised scores) for a range of Z scores:

Psychometric Conversion Table

PsyAsia’s Psychometric Training Course attendees will recall that to calculate a Z score from a raw score one uses the following formula:

Z score = Raw Score minus Mean divided by Standard Deviation

To convert from any other standard score scale into a Z score, one simply subtracts the mean of the other standard scale from the standard scale score and divides by the standard deviation of the standard score scale.

So, to convert a T score into a Z score:

Z score = T Score minus mean of T score scale (50) divided by standard deviation of a T score scale (10).