title: Skew-t fits to mortality data--can a Gaussian-related distribution replace the Gompertz-Makeham as the basis for mortality studies?
abstract: Gompertz-related distributions have dominated mortality studies for 187 years. However, nonrelated distributions also fit well to mortality data. These compete with the Gompertz and Gompertz-Makeham data when applied to data with varying extents of truncation, with no consensus as to preference. In contrast, Gaussian-related distributions are rarely applied, despite the fact that Lexis in 1879 suggested that the normal distribution itself fits well to the right of the mode. Study aims were therefore to compare skew-t fits to Human Mortality Database data, with Gompertz-nested distributions, by implementing maximum likelihood estimation functions (mle2, R package bbmle; coding given). Results showed skew-t fits obtained lower Bayesian information criterion values than Gompertz-nested distributions, applied to low-mortality country data, including 1711 and 1810 cohorts. As Gaussian-related distributions have now been found to have almost universal application to error theory, one conclusion could be that a Gaussian-related distribution might replace Gompertz-related distributions as the basis for mortality studies.
authors.affiliation: Department of Clinical and Molecular Biochemistry, Pomeranian Medical University, ul. Powstańców Wlkp. 72, 70-111 Szczecin, Poland. jeremyclarkmel@gmail.com
authors.forename: Jeremy S C
authors.initials: JS
authors.lastname: Clark
authors.forename: Mariusz
authors.initials: M
authors.lastname: Kaczmarczyk
authors.forename: Zbigniew
authors.initials: Z
authors.lastname: Mongiało
authors.forename: Paweł
authors.initials: P
authors.lastname: Ignaczak
authors.forename: Andrzej A
authors.initials: AA
authors.lastname: Czajkowski
authors.forename: Przemysław
authors.initials: P
authors.lastname: Klęsk
authors.forename: Andrzej
authors.initials: A
authors.lastname: Ciechanowicz
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001499:Bayes Theorem; D015331:Cohort Studies; D016208:Databases, Factual / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D015993:Life Tables; D016013:Likelihood Functions; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D009026:Mortality; D016011:Normal Distribution