STATISTICAL SHORT-CUT METHODS FOR THE RAPID LOCATION OF PEAK ANOMALY POSITIONS IN 2-DIMENSIONAL CRYSTALLOGRAPHIC DATA HISTOGRAMS - APPLICATION OF ORDER-STATISTICS TO CRYSTALLOGRAPHIC DATA-PROCESSING/

Statistical short-cut procedures involving the median, midrange and th e mean are presented as methods for location of peak/anomaly positions in area-detector data. These methods test for normal distribution in uniform background intensities in which peak/anomaly magnitudes are co nsidered as outlying data. Typically, the tests are applied to large d ata arrays where the background distributions are near normal with the statistic mean similar or equal to median similar or equal to [(x(1:n ) + x(n:n))(1/2)]. For data arrays with large intensity outliers, the statistic (x(1:n) + x(n:n) - 2 x median) and (mean - median) will be b oth greater than zero. If the outliers are censored, then ideally the above statistics will be equal to zero. Peak/anomaly pixel positions a re identified as those pixels with magnitudes greater than the magnitu de of the smallest censored point.