Opinion ID: 1679655
Heading Depth: 1
Heading Rank: 4

Heading: method of calculating statistical probability

Text: In order to make a statistical evaluation of a declared match, it is necessary to know how frequently a genotype occurs in the relevant reference population. This process is determined according to population genetics principles as previously stated. Mihalovich agreed that there were statistics regarding known observations of DQ Alpha type in segments of the population and in certain segments of the population that are used to make that analysis. Those statistics come from a wide variety of sources, including FSA's collection of data made over a period of years, Dr. Erlich's laboratory, and other sources not confined to the forensics field. Once the numbers are compiled, a statistical analysis is done to determine the percentage of the population that would have a particular DQ Alpha type. That is done for all 21 types. In doing that analysis, one method is the actual counting method, whereby one actually counts the number of people that have the particular type and/or the data are gathered from a number of people and counted as to how many times a particular type occurs within that population size. The other method is to calculate what the expected type would be using the formula referred to as the Hardy-Weinberg equation. Although Mihalovich is not a qualified population geneticist, she was permitted to give this testimony. It is with this generalized testimony on the method of calculation of the statistical probability data in mind that we examine the defendant's contention that PCR DNA evidence was improperly admitted. However, to address this issue and those which follow, it is necessary to discuss the proper evidentiary standard for determining the admissibility of PCR DQ Alpha test results, as this testing presents new scientific evidence.