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Abstract
In this paper, we use a regression model for modeling bounded outcome scores (BOS), where the outcome is Kumaraswamy distributed. Similar to the Beta distribution, this distribution can take a variety of shapes while being computationally easier to use. Thus, it is deemed as a suitable alternative distribution to the Beta in modeling bounded random processes. In the proposed model, the median of a bounded response is modeled by the linear predictors which is defined through regression parameters and explanatory variables. We obtained the maximum likelihood estimates (MLE) of the parameters, provided closed-form expressions for the score functions and Fisher information matrix, and presented some diagnostic measures. We conducted Monte Carlo simulations to investigate the finite-sample performance of the MLEs of the parameters. Finally, two practical applications of this model to the real data sets are presented and discussed.
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References
-
Arostegui, I., Núñezâ€Antón, V., & Quintana, J. M. (2007). Analysis of the short formâ€36 (SFâ€36): the betaâ€binomial distribution approach. Statistics in medicine, 26(6), 1318-1342.
Atkinson, A. C., & Atkinson, A. C. (1985). Plots, transformations and regression; an introduction to graphical methods of diagnostic regression analysis. Retrieved from
Bottai, M., Cai, B., & McKeown, R. E. (2010). Logistic quantile regression for bounded outcomes. Statistics in medicine, 29(2), 309-317.
Cordeiro, G. M., Nadarajah, S., & Ortega, E. M. (2012). The Kumaraswamy Gumbel distribution. Statistical Methods & Applications, 21(2), 139-168.
Cordeiro, G. M., Ortega, E. M., & Nadarajah, S. (2010). The Kumaraswamy Weibull distribution with application to failure data. Journal of the Franklin Institute, 347(8), 1399-1429.
Cramer, J. A., Perrine, K., Devinsky, O., Bryantâ€Comstock, L., Meador, K., & Hermann, B. (1998). Development and crossâ€cultural translations of a 31â€item quality of life in epilepsy inventory. Epilepsia, 39(1), 81-88.
de Pascoa, M. A., Ortega, E. M., & Cordeiro, G. M. (2011). The Kumaraswamy generalized gamma distribution with application in survival analysis. Statistical Methodology, 8(5), 411-433.
Ferrari, S., & Cribari-Neto, F. (2004). Beta regression for modelling rates and proportions. Journal of Applied Statistics, 31(7), 799-815.
Griffiths, W., Carter Hill, R., & Judge, G. G. (1993). Learning and practicing econometrics.
Hu, C., Yeilding, N., Davis, H. M., & Zhou, H. (2011). Bounded outcome score modeling: application to treating psoriasis with ustekinumab. Journal of pharmacokinetics and pharmacodynamics, 38(4), 497-517.
Hunger, M., Baumert, J., & Holle, R. (2011). Analysis of SF-6D index data: is beta regression appropriate? Value in Health, 14(5), 759-767.
Hunger, M., Döring, A., & Holle, R. (2012). Longitudinal beta regression models for analyzing health-related quality of life scores over time. BMC medical research methodology, 12(1), 144.
Hutton, J. L., & Stanghellini, E. (2011). Modelling bounded health scores with censored skewâ€normal distributions. Statistics in medicine, 30(4), 368-376.
Jones, M. (2009). Kumaraswamy’s distribution: A beta-type distribution with some tractability advantages. Statistical Methodology, 6(1), 70-81.
Kieschnick, R., & McCullough, B. D. (2003). Regression analysis of variates observed on (0, 1): percentages, proportions and fractions. Statistical modelling, 3(3), 193-213.
Kızılaslan, F., & Nadar, M. (2016). Estimation and prediction of the Kumaraswamy distribution based on record values and inter-record times. Journal of Statistical Computation and Simulation, 86(12), 2471-2493.
Kumaraswamy, P. (1980). A generalized probability density function for double-bounded random processes. Journal of Hydrology, 46(1-2), 79-88.
Lesaffre, E., Rizopoulos, D., & Tsonaka, R. (2006). The logistic transform for bounded outcome scores. Biostatistics, 8(1), 72-85.
McCullagh, P., & Nelder, J. A. (1989). Generalized Linear Models, no. 37 in Monograph on Statistics and Applied Probability: Chapman & Hall.
Mitnik, P. A., & Baek, S. (2013). The Kumaraswamy distribution: median-dispersion re-parameterizations for regression modeling and simulation-based estimation. Statistical Papers, 1-16.
Nocedal, J., & Wright, S. (1999). Numerical Optimization Springer-Verlag. New York.
Press, W., Teukolsky, S., Vetterling, W., & Flannery, B. (2007). Section 10.9: Quasi-newton or variable metric methods in multidimensions. Numerical recipes The art of scientific computing.
Smithson, M., & Verkuilen, J. (2006). A better lemon squeezer? Maximum-likelihood regression with beta-distributed dependent variables. Psychological methods, 11(1), 54.
Verkuilen, J., & Smithson, M. (2012). Mixed and mixture regression models for continuous bounded responses using the beta distribution. Journal of Educational and Behavioral Statistics, 37(1), 82-113.
Wewers, M. E., & Lowe, N. K. (1990). A critical review of visual analogue scales in the measurement of clinical phenomena. Research in nursing & health, 13(4), 227-236.
Xu, X. S., Samtani, M., Yuan, M., & Nandy, P. (2014). Modeling of bounded outcome scores with data on the boundaries: Application to disability assessment for dementia scores in Alzheimer’s disease. The AAPS journal, 16(6), 1271-1281.
Xu, X. S., Samtani, M. N., Dunne, A., Nandy, P., Vermeulen, A., De Ridder, F., & Initiative, A. s. D. N. (2013). Mixed-effects beta regression for modeling continuous bounded outcome scores using NONMEM when data are not on the boundaries. Journal of pharmacokinetics and pharmacodynamics, 40(4), 537-544.