Opinion ID: 1989907
Heading Depth: 3
Heading Rank: 2

Heading: Weighted Averaging Algorithm

Text: During the supplemental remand proceedings, source code analysis revealed the use of a calculation referred to as the weighted averaging algorithm. In short, this algorithm relates to the manner in which the IR result is calculated. This technology measures the effect of breath alcohol on an infrared signal. In order to calculate the result, the device is programmed to calculate a reading every quarter of a second, based on measurements taken every 8.192 milliseconds. The reported IR result is then computed by means of the algorithm, which places proportionately greater weight on the later measurements than on the earlier ones. In operation, the algorithm directs that the first two readings are averaged, and that value is averaged further with each successive reading. The effect is that the measurement is calculated to place greater and greater weight on the readings taken as the sample of breath continues. Defendants attack the use of this methodology as scientifically unsound. They point out, correctly, that it is neither an average nor technically even a weighted average. They further assert, however, that the use of this algorithm is evidence of a scientifically unsound device operated by inherently flawed software. We do not find merit in these arguments. To be sure, the calculation is not an average in accordance with the strict mathematical definition. It is, however, in a more general sense, a calculation designed to accord greater weight to that part of the breath sample that enters the cuvette at the end. In doing so, it gives greater weight to the breath that, inevitably, includes the deepest air drawn from the lung. It therefore focuses the analysis on the portion of the breath sample that most accurately represents the subject's BAC. In this manner, the weighted averaging algorithm seeks to achieve a more accurate result. We discern nothing in defendants' attacks on this weighted averaging algorithm that persuades us that it is inherently flawed or that it leads to an inaccurate measurement of BAC.