Martin Šefl gave a seminar presentation to undergraduate students from Whitman College in Walla Walla, Washington. His presentation, which is a part of the Mathematical Sciences Foundry Talks series, explained how a principal component regression was used to estimate the total amount of plutonium in the entire skeleton, based on the activity concentrations in a limited subset of bones. This approach is preferred to calculating an arithmetic mean, because it reduces the risk of bias for non-representative bone sampling, utilizes all available information, and reduces the uncertainty.