Heterogeneity ruses: some surprising effects and paradoxes of survival

Event Date: 3 October 2024

Speaker: Visiting Professor Maxim Finkelstein, University of the Free State, South Africa

Time: 2-3pm

Location: Strathclyde Business School, CW507B

Several survival models in heterogeneous settings are considered.  Heterogeneity in the failure rates of subpopulations results (as a specific case) in the famous failure rate paradox when the failure rate of a mixture of items with constant failure rates is decreasing. Random failure rate of a system that is due to a point process of shocks that increases it at random times on fixed values also results in this ‘bending down’ property for the corresponding failure rates. Similar effect is observed and justified when analyzing the extreme shock models with memory. Finally, another paradox when, due to heterogeneity in a vital parameter of a model, a terminating point process with decreasing rate after ‘mixing’ becomes a non-terminating one with increasing rate is described. Those are the impacts of heterogeneity that are discussed from the unified perspective that employs the ‘principle’: the weaker subpopulations are dying out first.

Published: 1 October 2024