Error Estimates because of Systematic Errors

Corrections to the Error Estimates because of Systematic Errors. The most useful error estimates should indude contributions from systematic errors which are as realistic as possible. K the uncertainty in the scale is estimated as p %, the standard deviations in the distance parameters should be corrected according to 

The possibility of including the contribution of the systematic intensity errors to the uncertainties has also been discussed.  

Inqxntant systematic errors may also be introduced by inaccurate assumptions about some parameters. The least-squares calculation will usually not converge if all the structural parameters are refined. Thus the asymmetry constants, [see equations (29) and (36)], are seldom refined, and very often 

It is possible to carry out the least-squares refinement treating some of the parameters formally as observables, i.e. the sum S [equation (77)] is increased if the parameters deviate from given values. However, in most cases the calculation is carried out simply with fixed values for some of the parameters. The least-squares criterion may still be applied, but the uncertainties in the fixed parameters should be included in the standard deviations, for example by the methods suggested by Kuchitsu or by Vilkov. A somewhat simpler approach, which probably is satisfactory in most cases, is described below.  

When the final least-squares parameters Xi with standard deviations af) have been obtained with some fixed parameters, additional refinements are carried out changing one of the assumed parameters [X at a time by a small amount. In this way, dXildXl may be obtained. A standard deviation for the assumed parameter (crj) is estimated, and the standard deviation for Xi calculated from 

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