A psychometric analysis of the measurement level of the rating scale, time trade-off, and standard gamble

Research output: Contribution to journalArticle

Karon F. Cook, Carol M. Ashton, Margaret M. Byrne, Baruch Brody, Jane Geraci, R. Brian Giesler, Makoto Hanita, Julianne Souchek, Nelda Wray

A fundamental assumption of utility-based analyses is that patient utilities for health states can be measured on an equal-interval scale. This assumption, however, has not been widely examined. The objective of this study was to assess whether the rating scale (RS), standard gamble (SG), and time trade-off (TTO) utility elicitation methods function as equal-interval level scales. We wrote descriptions of eight prostate-cancer-related health states. In interviews with patients who had newly diagnosed, advanced prostate cancer, utilities for the health states were elicited using the RS, SG, and TTO methods. At the time of the study, 77 initial and 73 follow-up interviews had been conducted with a consecutive sample of 77 participants. Using a Rasch model, the boundaries (Thurstone Thresholds) between four equal score sub-ranges of the raw utilities were mapped onto an equal-interval logit scale. The distance between adjacent thresholds in logit units was calculated to determine whether the raw utilities were equal-interval. None of the utility scales functioned as interval-level scales in our sample. Therefore, since interval-level estimates are assumed in utility-based analyses, doubt is raised regarding the validity of findings from previous analyses based on these scales. Our findings need to be replicated in other contexts, and the practical impact of non-interval measurement on utility-based analyses should be explored. If cost-effectiveness analyses are not found to be robust to violations of the assumption that utilities are interval, serious doubt will be cast upon findings from utility-based analyses and upon the wisdom of expending millions in research dollars on utility-based studies.

Original languageEnglish (US)
Pages (from-to)1275-1285
Number of pages11
JournalSocial Science and Medicine
Volume53
Issue number10
DOIs
StatePublished - Sep 18 2001

PMID: 11676400

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A psychometric analysis of the measurement level of the rating scale, time trade-off, and standard gamble. / Cook, Karon F.; Ashton, Carol M.; Byrne, Margaret M.; Brody, Baruch; Geraci, Jane; Giesler, R. Brian; Hanita, Makoto; Souchek, Julianne; Wray, Nelda.

In: Social Science and Medicine, Vol. 53, No. 10, 18.09.2001, p. 1275-1285.

Research output: Contribution to journalArticle

Harvard

Cook, KF, Ashton, CM, Byrne, MM, Brody, B, Geraci, J, Giesler, RB, Hanita, M, Souchek, J & Wray, N 2001, 'A psychometric analysis of the measurement level of the rating scale, time trade-off, and standard gamble' Social Science and Medicine, vol. 53, no. 10, pp. 1275-1285. https://doi.org/10.1016/S0277-9536(00)00409-3

APA

Cook, K. F., Ashton, C. M., Byrne, M. M., Brody, B., Geraci, J., Giesler, R. B., ... Wray, N. (2001). A psychometric analysis of the measurement level of the rating scale, time trade-off, and standard gamble. Social Science and Medicine, 53(10), 1275-1285. https://doi.org/10.1016/S0277-9536(00)00409-3

Vancouver

Cook KF, Ashton CM, Byrne MM, Brody B, Geraci J, Giesler RB et al. A psychometric analysis of the measurement level of the rating scale, time trade-off, and standard gamble. Social Science and Medicine. 2001 Sep 18;53(10):1275-1285. https://doi.org/10.1016/S0277-9536(00)00409-3

Author

Cook, Karon F. ; Ashton, Carol M. ; Byrne, Margaret M. ; Brody, Baruch ; Geraci, Jane ; Giesler, R. Brian ; Hanita, Makoto ; Souchek, Julianne ; Wray, Nelda. / A psychometric analysis of the measurement level of the rating scale, time trade-off, and standard gamble. In: Social Science and Medicine. 2001 ; Vol. 53, No. 10. pp. 1275-1285.

BibTeX

@article{242bcbc2c2da459dbe2afdbf48573721,
title = "A psychometric analysis of the measurement level of the rating scale, time trade-off, and standard gamble",
abstract = "A fundamental assumption of utility-based analyses is that patient utilities for health states can be measured on an equal-interval scale. This assumption, however, has not been widely examined. The objective of this study was to assess whether the rating scale (RS), standard gamble (SG), and time trade-off (TTO) utility elicitation methods function as equal-interval level scales. We wrote descriptions of eight prostate-cancer-related health states. In interviews with patients who had newly diagnosed, advanced prostate cancer, utilities for the health states were elicited using the RS, SG, and TTO methods. At the time of the study, 77 initial and 73 follow-up interviews had been conducted with a consecutive sample of 77 participants. Using a Rasch model, the boundaries (Thurstone Thresholds) between four equal score sub-ranges of the raw utilities were mapped onto an equal-interval logit scale. The distance between adjacent thresholds in logit units was calculated to determine whether the raw utilities were equal-interval. None of the utility scales functioned as interval-level scales in our sample. Therefore, since interval-level estimates are assumed in utility-based analyses, doubt is raised regarding the validity of findings from previous analyses based on these scales. Our findings need to be replicated in other contexts, and the practical impact of non-interval measurement on utility-based analyses should be explored. If cost-effectiveness analyses are not found to be robust to violations of the assumption that utilities are interval, serious doubt will be cast upon findings from utility-based analyses and upon the wisdom of expending millions in research dollars on utility-based studies.",
keywords = "Cost utility analysis, Cost-effectiveness, Health-state preferences, Preference weights, Psychometrics, Quality-adjusted life, Utility measurement",
author = "Cook, {Karon F.} and Ashton, {Carol M.} and Byrne, {Margaret M.} and Baruch Brody and Jane Geraci and Giesler, {R. Brian} and Makoto Hanita and Julianne Souchek and Nelda Wray",
year = "2001",
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doi = "10.1016/S0277-9536(00)00409-3",
language = "English (US)",
volume = "53",
pages = "1275--1285",
journal = "Social Science and Medicine",
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}

RIS

TY - JOUR

T1 - A psychometric analysis of the measurement level of the rating scale, time trade-off, and standard gamble

AU - Cook, Karon F.

AU - Ashton, Carol M.

AU - Byrne, Margaret M.

AU - Brody, Baruch

AU - Geraci, Jane

AU - Giesler, R. Brian

AU - Hanita, Makoto

AU - Souchek, Julianne

AU - Wray, Nelda

PY - 2001/9/18

Y1 - 2001/9/18

N2 - A fundamental assumption of utility-based analyses is that patient utilities for health states can be measured on an equal-interval scale. This assumption, however, has not been widely examined. The objective of this study was to assess whether the rating scale (RS), standard gamble (SG), and time trade-off (TTO) utility elicitation methods function as equal-interval level scales. We wrote descriptions of eight prostate-cancer-related health states. In interviews with patients who had newly diagnosed, advanced prostate cancer, utilities for the health states were elicited using the RS, SG, and TTO methods. At the time of the study, 77 initial and 73 follow-up interviews had been conducted with a consecutive sample of 77 participants. Using a Rasch model, the boundaries (Thurstone Thresholds) between four equal score sub-ranges of the raw utilities were mapped onto an equal-interval logit scale. The distance between adjacent thresholds in logit units was calculated to determine whether the raw utilities were equal-interval. None of the utility scales functioned as interval-level scales in our sample. Therefore, since interval-level estimates are assumed in utility-based analyses, doubt is raised regarding the validity of findings from previous analyses based on these scales. Our findings need to be replicated in other contexts, and the practical impact of non-interval measurement on utility-based analyses should be explored. If cost-effectiveness analyses are not found to be robust to violations of the assumption that utilities are interval, serious doubt will be cast upon findings from utility-based analyses and upon the wisdom of expending millions in research dollars on utility-based studies.

AB - A fundamental assumption of utility-based analyses is that patient utilities for health states can be measured on an equal-interval scale. This assumption, however, has not been widely examined. The objective of this study was to assess whether the rating scale (RS), standard gamble (SG), and time trade-off (TTO) utility elicitation methods function as equal-interval level scales. We wrote descriptions of eight prostate-cancer-related health states. In interviews with patients who had newly diagnosed, advanced prostate cancer, utilities for the health states were elicited using the RS, SG, and TTO methods. At the time of the study, 77 initial and 73 follow-up interviews had been conducted with a consecutive sample of 77 participants. Using a Rasch model, the boundaries (Thurstone Thresholds) between four equal score sub-ranges of the raw utilities were mapped onto an equal-interval logit scale. The distance between adjacent thresholds in logit units was calculated to determine whether the raw utilities were equal-interval. None of the utility scales functioned as interval-level scales in our sample. Therefore, since interval-level estimates are assumed in utility-based analyses, doubt is raised regarding the validity of findings from previous analyses based on these scales. Our findings need to be replicated in other contexts, and the practical impact of non-interval measurement on utility-based analyses should be explored. If cost-effectiveness analyses are not found to be robust to violations of the assumption that utilities are interval, serious doubt will be cast upon findings from utility-based analyses and upon the wisdom of expending millions in research dollars on utility-based studies.

KW - Cost utility analysis

KW - Cost-effectiveness

KW - Health-state preferences

KW - Preference weights

KW - Psychometrics

KW - Quality-adjusted life

KW - Utility measurement

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UR - http://www.scopus.com/inward/citedby.url?scp=0034840639&partnerID=8YFLogxK

U2 - 10.1016/S0277-9536(00)00409-3

DO - 10.1016/S0277-9536(00)00409-3

M3 - Article

VL - 53

SP - 1275

EP - 1285

JO - Social Science and Medicine

T2 - Social Science and Medicine

JF - Social Science and Medicine

SN - 0277-9536

IS - 10

ER -

ID: 3194469