Health  Vol.4 No.10 , October 2012
Pairwise comparisons in the analysis of carcinogenicity data
ABSTRACT
Analysis of carcinogenicity data generally involves a trend test across all dose groups and a pairwise comparison of the high dose group with the control. The most commonly used test for a positive trend is the Cochran-Armitage test. This test is asymptotically normal. For the pairwise comparison of the high dose group with the control group, we propose two modifications: the first modification is to apply the test on the data from high dose and control groups after dropping the data from the low and the medium dose groups; the second modification is to adjust the test conditional on data from all dose groups. We compare the power performance of these two modifications for the pairwise comparisons.

Cite this paper
Rahman, M. and Tiwari, R. (2012) Pairwise comparisons in the analysis of carcinogenicity data. Health, 4, 910-918. doi: 10.4236/health.2012.410139.
References
[1]   Cochran, W.G. (1954) Some methods of strengthening the common χ2 tests. Biometrics, 10, 417-451. Hdoi:10.2307/3001616

[2]   Armitage, P. (1955) Tests for linear trend in proportions and frequencies. Biometrics, 11, 375-386. Hdoi:10.2307/3001775

[3]   Tarone, R.E. (1975) Test for trend in life table analysis. Biometrika, 62, 679-690. Hdoi:10.1093/biomet/62.3.679

[4]   Tarone, R.E. (1982) The use of historical control information in testing for a trend in Poisson means. Biometrics, 38, 457-462. Hdoi:10.2307/2530459

[5]   Hoel, D.G. and Yanagawa, T. (1986) Incorporating historical controls in testing for a trend in proportions. Journal of the American Statistical Association, 81, 1095-1099. Hdoi:10.1080/01621459.1986.10478379

[6]   Tamura, R.N. and Young, S.S. (1986) The incorporation of historical control information in tests and proportions: Simulation study of Tarone’s Procedure. Biometrics, 42, 343-349. Hdoi:10.2307/2531054

[7]   Peto, R., Pike, M.C., Day, N.E., Gray, R.G.K, Lee, P.N. Parish, S., Peto, J., Richards, S. and Wahrendorf, J. (1980) Guidelines for sample sensitive significance test for carcinogenic effects in long-term animal experiments. IARC Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans, Suppl. 2, Long-Term and Short-Term Screening Assays for Carcinogens: A Critical Appraisal, IARC, Lyon, 311-426.

[8]   Bailer, A.J. and Portier, C.J. (1988) Effects of treatment-induced mortality and tumor-induced mortality on tests for carcinogenicity in small samples. Biometrics, 44, 417-431. Hdoi:10.2307/2531856

[9]   Mehta, C.R. and Patel, N.R. and Senchaudhuri, P. (1998) Exact power and sample-size computations for the Cochran-Armitage trend test. Biometrics, 54, 1615-1621. Hdoi:10.2307/2533685

[10]   Hothorn, L.A., Sill, M. and Schaarschmidt, F. (2010) Evaluation of incidence rates in pre-clinical studies using a Williams-type procedure. The International Journal of Biostatistics, 6, 1557-4679. Hdoi:10.2202/1557-4679.1180

[11]   Hothorn, L.A. and Bretz, F. (2000) Evaluation of animal carcinogenicity studies: Cochran-armitage trend test vs. multiple contrast tests. Biometrical Journal, 42, 553-567. Hdoi:10.1002/1521-4036(200009)42:5<553::AID-BIMJ553>3.0.CO;2-R

[12]   SAS Institute Inc., (2009) Multtest Procedure. SAS User’s Guide 9.2, 2nd Edition, SAS Institute Inc., Cary, 4176-4242.

 
 
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