11institutetext: Knowledge-based Systems and Document Processing Research Group Faculty of Computer Science Otto-von-Guericke-University Magdeburg 11email: katrin.krieger@ovgu.de
2.5. Construction and analysis of static life table
We constructed the static life table of Q. chungiipopulation by following the definition in Jones (2021) (Table 1). Survivorship and mortality curves were derived from the life table to assess mortality risks across age classes. We applied smoothing approach (Wratten and Fry 1980) to deal with the issue of negative number of individuals died during the observational period (nDx ). For example, the observed number of individuals alive in age class 3 (nN3 = 21) is smaller than that in age class 4 (nN4 = 34), then the estimated nD3 =nN3 \(-\)nN4 would be a negative value. The smoothing approach assumes an equal proportional change innNx in an interval centered at such age class (2–4 in this case). We calculated the average value ( \(\mu\)) and the difference between the maximum and minimum values ( ) ofnNx from the three age classes. The estimated of nNx after smoothing arenN2* \(=\mu-\frac{\text{∆}}{\text{3}}\),nN3* \(=\mu\), andnN4* \(=\mu+\frac{\text{∆}}{\text{3}}.\)
All the above analyses were performed in R 4.3.1 (R Development Core Team 2023), and the graphs were created using the “ggplot2” package in R (Wickham 2016).