Statistical Approaches to the Design of Toxicology Studies

Shayne C. Gad1

1 Gad Consulting Services, Raleigh, North Carolina
Publication Name:  Current Protocols in Toxicology
Unit Number:  Unit 1.2
DOI:  10.1002/0471140856.tx0102s00
Online Posting Date:  May, 2001
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Abstract

Application of statistics to toxicological studies involves hypothesis testing, model fitting, and reduction of dimensionality. This unit reviews statistical approaches to data (i.e., descriptive statistics, experimental design, outliers and rounding of numbers, and specific applications) and includes a set of decision trees to assist in choosing the appropriate methods.

     
 
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Table of Contents

  • Descriptive Statistics
  • Experimental Design
  • Outliers and Rounding of Numbers
  • Methods
  • Applications
  • Screening Studies
  • New Approaches to Statistical Analysis
  • Literature Cited
  • Figures
  • Tables
     
 
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Materials

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Figures

  •   FigureFigure 1.2.1 Overall decision tree for selecting statistical procedures. See Gad () for an explanation of the statistical methods.
  •   FigureFigure 1.2.2 Decision tree for selecting hypothesis‐testing procedure. *, if plot does not clearly demonstrate lack of normality, exact test may be employed; +, if continuous data, Kolmongorox‐Smirnov test may be used; −, if discontinuous data, χ2 goodness‐of‐fit test may be used. See Gad () for an explanation of the statistical methods.
  •   FigureFigure 1.2.3 Decision tree for selecting modeling procedures. See Gad () for an explanation of the statistical methods.
  •   FigureFigure 1.2.4 Decision tree for selecting reduction of dimensionality procedures. See Gad () for an explanation of the statistical methods.
  •   FigureFigure 1.2.5 Example of control chart used to prescreen (i.e., explore and identify influential) data from a portion of a functional observational battery.
  •   FigureFigure 1.2.6 Effective two‐dimensional visual display of three‐dimensional data. A correlative plot of a rabbit dermal study with white blood cell counts.

Videos

Literature Cited

Literature Cited
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   Beyer, W.H. 1976. Handbook of Tables for Probability and Statistics. pp. 269‐378,409‐413. Chemical Rubber Company, Cleveland, Ohio.
   Bliss, C.I. 1965. Statistical relations in fertilizer inspection. Bulletin, p. 674. Connecticut Agricultural Experiment Station, New Haven, Conn.
   Cox, D.R. and Stuart, A. 1955. Some quick tests for trend in location and dispersion. Biometrics 42:80‐95.
   Fears, T.R., Tarone, R.E., and Chu, K.C. 1977. False‐positive and false‐negative rates for carcinogenicity screens. Cancer Res. 27:1941‐1945.
   Gad, S.C. 1998. Statistics and Experimental Design for Toxicologists, 3rd ed. CRC Press, Boca Raton, Fla.
   Krewski, D. and Franklin, C. 1991. Statistics in Toxicology. Gordon and Breach Science Publishers, N.Y.
   Loeb, W.F. and Quimby, F.W. 1989. The Clinical Chemistry of Laboratory Animals. Pergamon Press, Elmsford N.Y.
   Montgomery, D.C. 1985. Introduction to Statistical Quality Control. John Wiley & Sons, N.Y.
   Montgomery, D.C. 1997. Design and Analysis of Experiments, 4th ed. John Wiley & Sons, N.Y.
   Oser, B.L. and Oser, M. 1956. Nutritional studies on rats on diets containing high levels of partial ester emulsifiers. II. Reproduction and lactation. J. Nutr. 60:429.
   Salsburg, D.S. 1977. Use of statistics when examining life time studies in rodents to detect carcinogenicity. J. Toxicol. Environ. Health 3:611‐628.
   Salsburg, D.S. 1986. Statistics for Toxicologists. Marcel Dekker, N.Y.
   Sheskin, D.J. 1997. Handbook of Parametric and Nonparametric Statistical Methods. CRC Press, Boca Raton, Fla.
   Tarone, R.E. 1975. Tests for trend in life table analysis. Biometrika 62:679‐682.
   Tufte, E.R. 1997. Visual Explanations. Graphic Press, Cheshire, Conn.
   Weil, C.S. 1970. Selection of the valid number of sampling units and a consideration of their combination in toxicological studies involving reproduction, teratogenesis or carcinogenesis. Food Cosmet. Toxicol. 8:177‐182.
   Weil, C.S. 1982. Statistical analysis and normality of selected hematologic and clinical chemistry measurements used in toxicologic studies. Arch. Toxicol. (Suppl.) 5:237‐253.
   Weil, C.S. and Gad, S.C. 1980. Applications of methods of statistical analysis to efficient repeated‐dose toxicologic tests. 2. Methods for analysis of body, liver, and kidney weight data. Toxicol. Appl. Pharmacol. 52:214‐226.
   Wilks, S.S. 1962. Mathematical Statistics. pp. 290‐291. John Wiley & Sons, N.Y.
   Zar, J.H. 1974. Biostatistical Analysis. p. 50. Prentice‐Hall, Englewood Cliffs, N.J.
   Zbinden, G., Elsner, J., and Boelsterli, U.A. 1984. Toxicological screening. Regul. Toxicol. Pharmacol. 4:275‐286.
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