This study introduces the Kavya–Manoharan Cosine–Gompertz (KMCG) distribution, a parsimonious three-parameter Gompertz-type model. Its main mathematical properties, including the distribution, density, survival, hazard-rate, quantile, moment, and order-statistic functions, are derived. The KMCG hazard rate is strictly increasing for all admissible parameter values, restricting its use to settings where an increasing hazard structure is appropriate. Parameters are estimated by maximum likelihood and Bayesian methods using Markov chain Monte Carlo (MCMC) sampling. Monte Carlo results generally show improved estimation accuracy with increasing sample size. Applications to Egyptian monthly real tax revenue and bank-client waiting-time data are used to compare KMCG with several Gompertz-type models. For the first dataset, KMCG provides favorable information criteria, although the Inverse Gompertz model performs slightly better on some goodness-of-fit measures. For the second dataset, KMCG yields the smallest information criteria and goodness-of-fit statistics, with bootstrap $ p $-values of $ 0.940 $, $ 0.976 $, and $ 0.952 $ for the Kolmogorov–Smirnov, Anderson–Darling, and Cramér–von Mises statistics, respectively. However, its AIC differs from that of the Transmuted Gompertz model by only about $ 0.129 $, indicating comparable performance. Bayesian estimates are broadly consistent with maximum likelihood results, while near-boundary estimates require cautious interpretation. Overall, KMCG provides a competitive alternative for positive-valued data with an increasing hazard structure, although its performance is data dependent.
Citation: Ayşe Metin KARAKAŞ, Fatma BULUT, Murat KARAKAŞ. A new Gompertz-type model with classical and Bayesian inference: applications to tax revenue and bank waiting-time data[J]. AIMS Mathematics, 2026, 11(10): 33105-33160. doi: 10.3934/math.20261298
This study introduces the Kavya–Manoharan Cosine–Gompertz (KMCG) distribution, a parsimonious three-parameter Gompertz-type model. Its main mathematical properties, including the distribution, density, survival, hazard-rate, quantile, moment, and order-statistic functions, are derived. The KMCG hazard rate is strictly increasing for all admissible parameter values, restricting its use to settings where an increasing hazard structure is appropriate. Parameters are estimated by maximum likelihood and Bayesian methods using Markov chain Monte Carlo (MCMC) sampling. Monte Carlo results generally show improved estimation accuracy with increasing sample size. Applications to Egyptian monthly real tax revenue and bank-client waiting-time data are used to compare KMCG with several Gompertz-type models. For the first dataset, KMCG provides favorable information criteria, although the Inverse Gompertz model performs slightly better on some goodness-of-fit measures. For the second dataset, KMCG yields the smallest information criteria and goodness-of-fit statistics, with bootstrap $ p $-values of $ 0.940 $, $ 0.976 $, and $ 0.952 $ for the Kolmogorov–Smirnov, Anderson–Darling, and Cramér–von Mises statistics, respectively. However, its AIC differs from that of the Transmuted Gompertz model by only about $ 0.129 $, indicating comparable performance. Bayesian estimates are broadly consistent with maximum likelihood results, while near-boundary estimates require cautious interpretation. Overall, KMCG provides a competitive alternative for positive-valued data with an increasing hazard structure, although its performance is data dependent.
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