Förskjutning av döden kring födelsedagen
In this thesis we adress a hypothesis that suggests that people can postpone their imminent death (given natural causes). The so-called "Postponement hypothesis" assumes that a meaningful occasion can act as a motivator to prolong life for a short amount of time. We consider a persons birthday as that meaningful occasion and analyze the hypothesis around this date by using tools from a statistical discipline known as Survival analysis. If the hypothesis is true it can be expected that the mortality rate should be lower a period before a person's birthday and, perhaps, higher shortly afterwards. We choose to set this period to a limit of 14 days. This would indicate that there is a force which postpones death for the population concerned. The datasets used in analysis are mortality data over people who lived to be Supercentenarian and Italian people who became older than 105 years, and also primarily a dataset for South African people who died in the year 2015. The mortality rate is summarised by hazard functions, which at each age expressed in days describes the dying rate of people who survived to this day. We thereafter apply various parametric models to the hazard, in order to discover any discrepancy around the birthdays. For this a t-test is conducted on the mean of the residuals mortality in the birthday period, to see if the mean is non-zero. This should be the case if the days around the birthdays are no di erent in terms of mortality rate compared to other days of the year. The results of our analysis show that no postponement of death can be seen for the examined dataset. Instead the data suggest that the mortality rate is actually higher both before and after the birthday. Speculations as to why this is the case might be a higher risk associated with the stress of preparing for the birthday.