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Why do we continue to use standardized mortality ratios for small area comparisons?

Why do we continue to use standardized mortality ratios for small area comparisons?
Why do we continue to use standardized mortality ratios for small area comparisons?
Public health practitioners are often faced with the necessity to compare the mortality experience of different geographical areas. Indirect standardization, producing a 'standardized mortality ratio' (SMR) is the most commonly used technique for doing this. However, as we show, indirect standardization is inappropriate for such comparisons, as SMRs for different geographical areas have different denominators. The fact that indirect standardization is usually chosen for this type of comparison is probably based on two beliefs: (1) that direct standardization yields only a rate rather than a more easily interpreted ratio or index; (2) that direct standardization cannot be carried out in many cases because the sub-group specific mortality rates in the groups to be compared are not available or, in at least some age classes, are based upon such small numbers as to be completely unreliable. In this paper we show that a simple index (the comparative mortality figure) can be calculated from the directly standardized rate in most cases. Using a comparison of the overall mortality experience of electoral wards in Sheffield between 1980 and 1987 we demonstrate also that the advantage gained by the smaller standard error of the SMR is outweighed by the bias inherent in its construction. We recommend that the SMR is used only when absolutely necessary, that is, in the rare circumstance when data are not available for the calculation of age- and sex-specific subgroup rates in the study population.
small area statistics, standardization
0957-4832
40-46
Julious, S.
574fbf4f-5965-4f45-a2d5-5a781cd7a718
Nicholl, J.
fd8967c7-7fbd-411f-8a57-9c5b6b7b63b4
George, S.
bdfc752b-f67e-4490-8dc0-99bfaeb046ca
Julious, S.
574fbf4f-5965-4f45-a2d5-5a781cd7a718
Nicholl, J.
fd8967c7-7fbd-411f-8a57-9c5b6b7b63b4
George, S.
bdfc752b-f67e-4490-8dc0-99bfaeb046ca

Julious, S., Nicholl, J. and George, S. (2001) Why do we continue to use standardized mortality ratios for small area comparisons? Journal of Public Health Medicine, 23 (1), 40-46.

Record type: Article

Abstract

Public health practitioners are often faced with the necessity to compare the mortality experience of different geographical areas. Indirect standardization, producing a 'standardized mortality ratio' (SMR) is the most commonly used technique for doing this. However, as we show, indirect standardization is inappropriate for such comparisons, as SMRs for different geographical areas have different denominators. The fact that indirect standardization is usually chosen for this type of comparison is probably based on two beliefs: (1) that direct standardization yields only a rate rather than a more easily interpreted ratio or index; (2) that direct standardization cannot be carried out in many cases because the sub-group specific mortality rates in the groups to be compared are not available or, in at least some age classes, are based upon such small numbers as to be completely unreliable. In this paper we show that a simple index (the comparative mortality figure) can be calculated from the directly standardized rate in most cases. Using a comparison of the overall mortality experience of electoral wards in Sheffield between 1980 and 1987 we demonstrate also that the advantage gained by the smaller standard error of the SMR is outweighed by the bias inherent in its construction. We recommend that the SMR is used only when absolutely necessary, that is, in the rare circumstance when data are not available for the calculation of age- and sex-specific subgroup rates in the study population.

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More information

Published date: March 2001
Keywords: small area statistics, standardization

Identifiers

Local EPrints ID: 24354
URI: http://eprints.soton.ac.uk/id/eprint/24354
ISSN: 0957-4832
PURE UUID: 91e3eaf2-413a-470a-b2ce-3f7079b4cf60

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Date deposited: 29 Mar 2006
Last modified: 22 Jul 2022 20:28

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Contributors

Author: S. Julious
Author: J. Nicholl
Author: S. George

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