The effect of data truncation on the measurability of Bijvoet differences

Theoretical expressions for the complementary cumulative function of the Bijvoet ratio X applicable to a truncated data set are worked out for a non-centrosymmetric crystal containing P anomalous scatterers in the unit cell [P = 1 and many (MN and MC cases)] besides a large number of normal scatterers. These expressions contain the truncation limit y_t as a parameter of the distribution. The results obtained are used to discuss the effect of data truncation arising from the non-observability of extremely weak reflections on the measurability of Bijvoet differences.