A note on the a priori estimation of R factors for constant-count-per-reflexion diffractometer experiments
Abstract
<h2>Acta Crystallographica</h2><h3></h3><h3>0365-110X</h3> <h2>short communications</h2> Volume 23 Part 6 Pages 1109-1110 December 1967 <h2>A note on the a priori estimation of R factors for constant-count-per-reflexion diffractometer experiments</h2> R. C. G. Killean Acta Cryst. (1967). 23, 1109 A note on the a priori estimation of R factors for constant-count-per-reflexion diffractometer experiments. By R. C. G. KILLEAN, Department of Physics, The University, St. Andrews, Scotland (Received 1 April 1967 and in revised form 27 June 1967) To obtain data capable of yielding an R factor of 10% the total number of counts per reflexion need not exceed 25, for low background reflexions, rising to 125 for a peak to background ratio of 1-5. An equation required to develop a constant-agreement analysis is derived which is based on a constant-count type experiment. It has been shown (Killean, 1967) that a constant-count, as distinct from a constant-time-per-reflexion diffractometer experiment, has certain advantages. In view of the high capital cost of automatic diffractometers it is relevant to consider what numerical value this constant count should be to achieve a given reliability index and, for the purposes of this paper, an ideal diffractometer experiment in which the errors in the data are due only to