Addressing the National Academy of Sciences' challenge: a method for statistical pattern comparison of striated tool marks

In February 2009, the National Academy of Sciences published a report entitled "Strengthening Forensic Science in the United States: A Path Forward." The report notes research studies must be performed to "…understand the reliability and repeatability…" of comparison methods commonly used in forensic science. Numerical classification methods have the ability to assign objective quantitative measures to these words. In this study, reproducible sets of ideal striation patterns were made with nine slotted screwdrivers, encoded into high-dimensional feature vectors, and subjected to multiple statistical pattern recognition methods. The specific methods employed were chosen because of their long peer-reviewed track records, widespread successful use for both industry and academic applications, rely on few assumptions on the data's underlying distribution, can be accompanied by standard confidence levels, and are falsifiable. For PLS-DA, correct classification rates of 97% or higher were achieved by retaining only eight dimensions (8D) of data. PCA-SVM required even fewer dimensions, 4D, for the same level of performance. Finally, for the first time in forensic science, it is shown how to use conformal prediction theory to compute identifications of striation patterns at a given level of confidence.     

Violence and Mental Illness: A New Analytic Approach

Empirical studies of violence and mental illness have used many different methods. Current state-of-the-art methods gather information from both subject and collateral interviews as well as official records. Typically these sources are treated as additive. Any report of a violent incident from any source is treated as true and all reported incidents are added to generate estimates of frequency. This paper presents a new statistical technique that uses the level of agreement between the sources of data to adjust those estimates. The evidence suggests that, although the additive technique for using multiple sources correctly estimates how many people are involved, it substantially underestimates the number of incidents. The new technique substantially reduces both false negatives and false positives.     

Yunnan,China: minority peoples observed

An account of the time which the author spent among the Iban more than 30 years ago. He describes the customs, festivals and way of life of a people who were still headhunters in recent memory. More particularly he explains how people who lived in longhouses the way their ancestors had lived were slowly brought to change their traditional beliefs, thus enabling development to take place.