Confidence intervals in temperature-based death time determination

•Death time determination (DTD) is a central competence in legal medicine.•Marshall and Hoare Method with Henßge parameters (MHH) is widely used in DTD.•Probability of 95%-confidence intervals (CI) of MHH is reduced by bias.•In the article formulae are derived for real CI probability under bias.•Corrected CIs can be computed by formulae in this article.

Marshall and Hoare’s double exponential model with Henßge’s parameters is a well known method for temperature based death time estimation. The authors give 95%-confidence intervals for their method. Since body cooling is a complex thermodynamical process, one has to take into account a potential bias of the estimator. This quantity measures the systematic error of the estimators underlying model. For confidence interval radius calculation a bias of 0 is presupposed, therefore the actual probability of the true death time value to lie in the 95%-confidence interval can be much lower than 95% in case of nonvanishing bias.As in case of nonstandard conditions the confidence intervals have a probability of containing the true death time value which even in case of small corrective factor errors of Δc = ±0.1 can be substantially smaller than the 95% claimed, the paper presents a formula for confidence intervals which keep a 95% probability in case of error Δc ⩽ ±0.1.