- Lumley T, Diehr P, Emerson S, Chen L. The importance of the normality assumption in large public health data sets. Ann. Rev. Pub. Health 23, 151–169 (2002).
- Zhou XH, Melfi CA, Hui SL. Methods for comparison of cost data. Ann. Intern. Med. 127, 752–756 (1997).
- Zhou XH, Gao S, Hui SL. Methods for comparing the means of two independent log-normal populations. Biometrics 53, 1129–1135 (1997).
- •First paper to discuss the problem associated with the standard tests for comparing means of two samples and derived a simple Z-score test for the equality of means of two log-normal distributions.
- Tu W Zhou XH. A Wald test comparing medical costs based on log-normal distributions with zero valued costs. Stat. Med. 18,2749-2761 (1999).
- Zhou XH, Tu W Comparison of several independent population means when their samples contain log-normal and possibly zero observations. Biometrics 55,645–651 (1999).
- •Improved on the Z-score test by deriving a likelihood ratio test that can also handle additional zero values.
- Zhou XH, Li C, Gao S, Tierney WM. Methods for comparing means of healthcare costs in a paired design study, Stat Med. 20,1703–1720 (2001).
- Duan N, Manning WG Jr, Morris CN, Newhouse JP. a comparison of alternative models for the demand for medical care. J. Business Econ. Stat. 1, 115–126 (1983).
- Hay SW, Olsen RJ. Let them eat cake: a note on comparing alternative models of the demand for medical care. J Business Econ. Stat. 2,279–282 (1984).
- Halvorsen R, Palmquist R. The interpretation of dummy variables in semilogarithmic equations. Am Econ. Rev 70,474–476 (1980).
- Guijarati, D. Basic Econometric. McGraw- Hill, NY, USA (1995).
- Duan N. Smearing estimate: a nonparametric retransformation method. J Am. Stat. Assoc. 78, 605–610 (1983).
- •First paper that looked at the retransformation bias and derived a smearing estimator for correcting for this type of bias.
- Manning WG. The logged dependent variable, heteroscedasticity and the retransformation problem. J Health Econ. 17,283–295 (1998).
- Mullahy J. Much ado about two: reconsidering retransformation and the two-part model in health econometrics. J Health Econ. 17,247–281 (1998).
- Zhou XH, Stroupe KT, Tierney WM. Regression analysis of healthcare charges with heterosdesticity. J. Royal Stat. Soc. Series C50,303–312 (2001).
- Welsh AH, Zhou XH. Estimating the retransformed mean in a heteroscedastic two-part model. (Submitted).
- Blough DK, Ramsey SD. Using generalized linear models to assess medical care costs. Health Serv. Outcomes Res. Methodology 1, 185–202 (2000).
- Manning WG, Mullahy J. Estimating log models: to transform or not to transform?J Health Econ. 20(4), 461–494 (2001).
- Diehr P, Yanez D, Ash A, Hornbrook M, Lin DY. Methods for analyzing healthcare utilization and costs. Ann. Rev 20, 125–144 (1999).
- Zhou XH, Gao S. Confidence intervals for the lognormal mean. Stat. Med. 16, 783–790 (1997).
- Taylor DJ, Kupper LL, Muller KE. Improved approximate confidence interval for the mean of a log-normal random variable. Stat. Med. 26,1443–1459 (2001).
- Tu W, Zhou XH. Pairwise comparisons of the means of skewed data. J Stat. Ran. Inference 88,59–74 (2000).
- Bang H, Tsiatis AA. Estimating medical costs with censored data. Biometrika 87, 329–343 (2000).
- Lin DY. Linear regression analysis of censored medical costs. Biostatistics 1, 35–47 (2000).
- Lin DY. Proportional means regression for censored cost data. Biometrics 56,775–778 (2000).
- Jiang H, Zhou XH. Bootstrap confidence intervals for medical costs with censored data. Stat. Med. (In Press) (2003).
Expert Review of Pharmacoeconomics & Outcomes Research
Volume 3, 2003 - Issue 5