TY - JOUR
T1 - It might be premature to reject the assumption of a power curve relationship between VAS and SG data
T2 - Three comments on stevens, McCabe and Brazier's mapping between VAS and SG data; results from the UK Hui index 2 valuation survey'
AU - Shmueli, Amir
PY - 2007/7
Y1 - 2007/7
N2 - In a recent paper in Health Economics, Stevens, McCabe and Brazier (Health Econ. 2006; 15: 527-533.) found that the cubic relationship between Visual Analog Scale (VAS) values and standard gamble (SG) utilities was superior to other functional forms in terms of explanatory power and predictive ability. Consequently, they question the reliance on the assumption of a power curve relationship, which was established, theoretically and empirically, in earlier works. This note argues that: (1) SMB's conclusions are incorrect. The estimated cubic function overfits the four data points, and is questionable with respect to the implied attitude toward relative risk. (2) The evaluation of the functional forms in terms of the individual predictions' mean absolute error is misleading and (3) correcting for heteroscedasticity improves the precision of the estimates and of the predictions.
AB - In a recent paper in Health Economics, Stevens, McCabe and Brazier (Health Econ. 2006; 15: 527-533.) found that the cubic relationship between Visual Analog Scale (VAS) values and standard gamble (SG) utilities was superior to other functional forms in terms of explanatory power and predictive ability. Consequently, they question the reliance on the assumption of a power curve relationship, which was established, theoretically and empirically, in earlier works. This note argues that: (1) SMB's conclusions are incorrect. The estimated cubic function overfits the four data points, and is questionable with respect to the implied attitude toward relative risk. (2) The evaluation of the functional forms in terms of the individual predictions' mean absolute error is misleading and (3) correcting for heteroscedasticity improves the precision of the estimates and of the predictions.
KW - Health state valuation
KW - HUI
KW - Power curve
KW - Standard gamble
KW - Visual analog scale
UR - http://www.scopus.com/inward/record.url?scp=34447645145&partnerID=8YFLogxK
U2 - 10.1002/hec.1188
DO - 10.1002/hec.1188
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C2 - 17177167
AN - SCOPUS:34447645145
SN - 1057-9230
VL - 16
SP - 755
EP - 758
JO - Health Economics (United Kingdom)
JF - Health Economics (United Kingdom)
IS - 7
ER -