On the practice of dichotomization of quantitative variables.

The authors examine the practice of dichotomization of quantitative measures, wherein relationships among variables are examined after 1 or more variables have been converted to dichotomous variables by splitting the sample at some point on the scale(s) of measurement. A common form of dichotomization is the median split, where the independent variable is split at the median to form high and low groups, which are then compared with respect to their means on the dependent variable. The consequences of dichotomization for measurement and statistical analyses are illustrated and discussed. The use of dichotomization in practice is described, and justifications that are offered for such usage are examined. The authors present the case that dichotomization is rarely defensible and often will yield misleading results.

[1]  Leland Wilkinson,et al.  Statistical Methods in Psychology Journals Guidelines and Explanations , 2005 .

[2]  J. A. Calvin.  Regression Models for Categorical and Limited Dependent Variables , 1998 .

[3]  Paul E. Meehl,et al.  Multivariate Taxometric Procedures: Distinguishing Types from Continua , 1997 .

[4]  S. Maxwell,et al.  Dichotomization, Partial Correlation, and Conditional Independence , 1996 .

[5]  G. De Soete,et al.  Clustering and Classification , 2019, Data-Driven Science and Engineering.

[6]  Larry E. Toothaker,et al.  Multiple Regression: Testing and Interpreting Interactions , 1991 .

[7]  B. Gorman,et al.  Some of the most common questions asked of statistical consultants: our favorite responses and recommended readings , 1993 .

[8]  S. Maxwell,et al.  Bivariate median splits and spurious statistical significance. , 1993 .

[9]  P. Meehl.  Factors and Taxa, Traits and Types, Differences of Degree and Differences in Kind , 1992 .

[10]  Mark Snyder,et al.  Taxonomic Analysis Redux: Some Statistical Considerations for Testing a Latent Class Model , 1991 .

[11]  P. Merenda,et al.  Brief Note on Graduate Training in Statistics, Methodology, and Measurement in Psychology , 1990 .

[12]  Ira H. Bernstein,et al.  Personality Moderating Variables: A Warning about Statistical Artifact and a Comparison of Analytic Techniques , 1990 .

[13]  John E. Hunter,et al.  Dichotomization of continuous variables: the implications for meta-analysis , 1990 .

[14]  Alan E. Kazdin,et al.  Graduate Training in Statistics, Methodology, and Measurement in Psychology: A Survey of PhD Programs in North America , 1990 .

[15]  Mark L. Miller,et al.  On the existence of discrete classes in personality: Is self-monitoring the correct joint to carve? , 1989 .

[16]  Mark Snyder,et al.  "To Carve Nature at Its Joints": On the Existence of Discrete Classes in Personality , 1985 .

[17]  Jacob Cohen.  The Cost of Dichotomization , 1983 .

[18]  D. Ozer,et al.  Two types of psychologists: Remarks on the Mendelsohn, Weiss, and Feimer contribution. , 1982 .

[19]  Maurice G. Kendall,et al.  Inference and relationship , 1979 .

[20]  Lloyd G. Humphreys,et al.  Doing Research the Hard Way: Substituting Analysis of Variance for a Problem in Correlational Analysis. , 1978 .

[21]  Lloyd G. Humphreys,et al.  Research on individual differences requires correlational analysis, not ANOVA , 1978 .

[22]  J. P. Das,et al.  Reading Achievement, IQ, and Simultaneous-Successive Processing. , 1977 .

[23]  Jacob Cohen,et al.  Applied multiple regression/correlation analysis for the behavioral sciences , 1979 .

[24]  L. Humphreys,et al.  Pseudo-Orthogonal and Other Analysis of Variance Designs Involving Individual-Differences Variables. , 1974 .

[25]  L. Humphreys,et al.  Jensen's theory of intelligence. , 1969 .

[26]  L. Humphreys,et al.  Jensen's Theory of Intelligence: A Rebuttal. , 1969 .

[27]  M. R. Novick,et al.  Statistical Theories of Mental Test Scores. , 1971 .

[28]  A. Jensen.  Patterns of mental ability and socioeconomic status. , 1968, Science.

[29]  J. Keats,et al.  Test theory. , 1967, Annual review of psychology.

[30]  Maurice G. Kendall,et al.  The Advanced Theory of Statistics, Vol. 2: Inference and Relationship , 1979 .

[31]  Kern W. Dickman,et al.  Sample and population score matrices and sample correlation matrices from an arbitrary population correlation matrix , 1962 .

[32]  Maurice G. Kendall,et al.  The advanced theory of statistics , 1945 .

[33]  P. F. Miller.  Statistical Procedures and their Mathematical Bases , 1941, Nature.

[34]  K. Pearson.  Mathematical contributions to the theory of evolution. VIII. On the correlation of characters not quantitatively measurable , 2022, Proceedings of the Royal Society of London.