### Abstract

Many commentators on neuropsychological assessment stress the disadvantages of expressing test scores in the form of percentile ranks. As a result, there is a danger of losing sight of the fundamentals: percentile ranks express scores in a form that is of greater relevance to the neuropsychologist than any alternative metric because they tell us directly how common or uncommon such scores are in the normative population. We advocate that, in addition to expressing scores on a standard metric, neuropsychologists should also routinely record the percentile rank of all test scores so that the latter are available when attempting to reach a formulation. In addition, it is argued that the current practice of expressing confidence limits on test scores on a standard score metric should be supplemented with confidence limits expressed as percentile ranks, because the latter provide a more direct and tangible indication of the uncertainty surrounding an observed score. Computer programs accompany this paper and can be used to obtain percentile rank confidence limits for Index scores (and FSIQs) on the WAIS-III or WISC-IV (these can be downloaded from the following web page: http://www.abdn.ac.uk/psy086/dept/PRCLME.htm).

Original language | English |
---|---|

Pages (from-to) | 193-204 |

Number of pages | 12 |

Journal | Clinical Neuropsychologist |

Volume | 23 |

Issue number | 2 |

DOIs | |

Publication status | Published - 2009 |

### Keywords

- percentiles
- percentile ranks
- confidence limits
- neuropsychological assessment
- psychometrics
- dissociations
- intervals
- errors

### Cite this

**Percentiles please : the case for expressing neuropsychological test scores and accompanying confidence limits as percentile ranks.** / Crawford, John R.; Garthwaite, Paul H.

Research output: Contribution to journal › Article

*Clinical Neuropsychologist*, vol. 23, no. 2, pp. 193-204. https://doi.org/10.1080/13854040801968450

}

TY - JOUR

T1 - Percentiles please

T2 - the case for expressing neuropsychological test scores and accompanying confidence limits as percentile ranks

AU - Crawford, John R.

AU - Garthwaite, Paul H.

PY - 2009

Y1 - 2009

N2 - Many commentators on neuropsychological assessment stress the disadvantages of expressing test scores in the form of percentile ranks. As a result, there is a danger of losing sight of the fundamentals: percentile ranks express scores in a form that is of greater relevance to the neuropsychologist than any alternative metric because they tell us directly how common or uncommon such scores are in the normative population. We advocate that, in addition to expressing scores on a standard metric, neuropsychologists should also routinely record the percentile rank of all test scores so that the latter are available when attempting to reach a formulation. In addition, it is argued that the current practice of expressing confidence limits on test scores on a standard score metric should be supplemented with confidence limits expressed as percentile ranks, because the latter provide a more direct and tangible indication of the uncertainty surrounding an observed score. Computer programs accompany this paper and can be used to obtain percentile rank confidence limits for Index scores (and FSIQs) on the WAIS-III or WISC-IV (these can be downloaded from the following web page: http://www.abdn.ac.uk/psy086/dept/PRCLME.htm).

AB - Many commentators on neuropsychological assessment stress the disadvantages of expressing test scores in the form of percentile ranks. As a result, there is a danger of losing sight of the fundamentals: percentile ranks express scores in a form that is of greater relevance to the neuropsychologist than any alternative metric because they tell us directly how common or uncommon such scores are in the normative population. We advocate that, in addition to expressing scores on a standard metric, neuropsychologists should also routinely record the percentile rank of all test scores so that the latter are available when attempting to reach a formulation. In addition, it is argued that the current practice of expressing confidence limits on test scores on a standard score metric should be supplemented with confidence limits expressed as percentile ranks, because the latter provide a more direct and tangible indication of the uncertainty surrounding an observed score. Computer programs accompany this paper and can be used to obtain percentile rank confidence limits for Index scores (and FSIQs) on the WAIS-III or WISC-IV (these can be downloaded from the following web page: http://www.abdn.ac.uk/psy086/dept/PRCLME.htm).

KW - percentiles

KW - percentile ranks

KW - confidence limits

KW - neuropsychological assessment

KW - psychometrics

KW - dissociations

KW - intervals

KW - errors

U2 - 10.1080/13854040801968450

DO - 10.1080/13854040801968450

M3 - Article

VL - 23

SP - 193

EP - 204

JO - Clinical Neuropsychologist

JF - Clinical Neuropsychologist

SN - 1385-4046

IS - 2

ER -