Abstract
This article investigates the problem of simultaneously testing the normality and homoscedasticity assumptions in a linear fixed effects model when we have grouped data. This has been facilitated by the assumption of a smooth alternative to the normal distribution. The smooth alternative is specified using Legendre polynomials, and the score statistic is derived under two scenarios: a common smooth alternative across the different groups, or different smooth alternatives across the different groups. A data-driven approach available in the literature is used for determining the order of the polynomials. For the null distribution of the score statistic, the accuracy of the asymptotic chi-squared distribution is numerically investigated under a one-way fixed effects model with balanced and unbalanced data. The results are illustrated with an example.
Similar content being viewed by others
References
Andrews, D. Ε., and Α. Μ. Herzberg. 1985. Data: A collection of problems from many fields for students and research workers. New York, NY: Springer-Verlag.
Bogdan, M. 1996. Data driven smooth tests for bivariate normality. Preprint IM PWr 42/96, Technical University of Wroclaw, Wroclaw, Poland.
Bogdan, M. 1999. Data driven smooth tests for bivariate normality. Journal of Multivariate Analysis 68:26–53.
Chang, C.-H., N. Pal, and J.-J. Lin. 2016. A revisit to test the equality of variances of several populations. Communications in Statistics—Simulation and Computation, to appear. https://doi.org/10.1080/03610918.2016.1202277
Inglot, T., and T. Ledwina. 1996. Asymptotic optimality of data-driven Neymans tests for uniformity. Annals of Statistics 24:1982–2019.
Inglot, T., W. Kallenberg, and T. Ledwina. 1997. Data driven smooth tests for composite hypotheses. Annals of Statistics 25:1222–1250.
Janic, Α., and T. Ledwina. 2009. Data-driven smooth tests for a location-scale family revisited. Journal of Statistical Theory and Practice 3:645–664.
Kallenberg, W., and T. Ledwina. 1995. Consistency and Monte Carlo simulation of a data driven version of smooth goodness-of-fit tests. Annals of Statistics 23:1594–1608.
Kallenberg, W., and T. Ledwina. 1997a. Data-driven smooth tests for composite hypotheses: Comparison of powers. Journal of Statistical Computation and Simulation 59:101–121.
Kallenberg, W., and T. Ledwina. 1997b. Data-driven smooth tests when the hypothesis is composite. Journal of the American Statistical Association 92:1094–1104.
Kallenberg, W., T. Ledwina, and E. Rafajlowicz. 1997. Testing bivariate independence and normality. Sankhyã, Series A 59:42–59.
Ledwina, T. 1994. Data-driven version of Neymans smooth test of fit. Journal of the American Statistical Association 89:1000–1005.
Mardia, K. V., and J. T. Kent. 1991. Rao score tests for goodness of fit and independence. Biometrika 78:355–363.
Montgomery, D. C. 2012. Design and analysis of experiments, 8th Ed. New York, NY: John Wiley.
Neyman, J. 1937. Smooth test for goodness of fit. Skandinaviska Aktuarietidskrift 20:149–199.
Peña, Ε. Α., and Ε. Η. Slate. 2006. Global validation of linear model assumptions. Journal of the American Statistical Association 101:341–354.
Rayner, J. C. W., O. Thas, and D. J. Best. 2009. Smooth tests of goodness of fit: Using R. New York, NY: John Wiley.
Reaven, G. M., and R G. Miller. 1979. An attempt to define the nature of chemical diabetes using a multidimensional analysis. Diabetologia 16:17–24.
Yang, Y. 2016. The simultaneous assessment of normality and homoscedasticity in some linear models. Doctoral dissertation submitted to the University of Maryland Baltimore County, Baltimore, MD.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Yang, Y., Mathew, T. The simultaneous assessment of normality and homoscedasticity in linear fixed effects models. J Stat Theory Pract 12, 66–81 (2018). https://doi.org/10.1080/15598608.2017.1320243
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1080/15598608.2017.1320243
Keywords
- Balanced data
- Legendre polynomials
- one-way fixed effects model
- score test
- smooth alternative
- unbalanced data