Authors: Richard Alden, Jim Stewart and Keith Watenpaugh

Contact: Keith Watenpaugh, Physical and Analytical Chemistry,

The Upjohn Company, Kalamazoo, MI49001, USA.

CRITIQ is used to examine multiply observed intensity data and to pick out the most variable reflections. A bdf containing replicated observations is read and a list of the reflections whose multiple observations exhibit the most variability is produced. The N most variable reflections according to each of four categories are listed. N is user specified. It is also possible to list all singly-observed reflections within a specified range of sinθ/λ.

Overview

Five different discrepancy lists are prepared; a separate compact list, in order of decreasing discrepancy, for each of the four ranking categories (see below), plus a merged list containing all ranked reflection intensities. The merged list is listed in reflection sort order. To aid editing, the merged list contains, in additon to the ranked observations, up to a specified maximum number of unranked observations for each reflection.

The ranking categories are as follows:

1. |K*I-Y|

2. (1-Y/(K*I))² (corresponds to the SCALE1 R-factor)

3. |K*I-Y| / σY

4. |K*I-Y| / σI

where I is the observed intensity(rel), Y is the mean intensity of a particular reflection and K is the scale constant for a particular scale group. For observations where I < 0.1, the value for category number 2 is not computed (i.e., the observation is not considered for ranking purposes in that category).

To clarify what is meant by "decreasing discrepancy" for a category, consider the observation which has the largest absolute value for the expression, K*I-Y. It will be ranked number one in category 1 above and will appear as such in the listing for that category. Of course it may also appear in one or more of the remaining three categories. This observation will also be listed in the merged set of all discrepancies under the reflection to which it belongs. All other observations for that reflection which have rankings in any of the four categories will also appear, as well as a user-specified maximum of unranked observations (if any), still for that same reflection.

File Assignments

Reads reflection data from the input archive bdf

Example

title ANALYZE NATIVE DATA AFTER INITIAL SCALING

CRITIQ 1 50

The listing will consist of the 50 largest discrepancies in each of the 4 categories with all scale group numbers and all data being involved. No singly observed reflections will be listed and Bijvoet pairs will not be considered as separate reflections. All shift numbers for which there are scale factors will be read from logical record lrrefl: of the input bdf.