Treatment of Anomalies

What should one do about anomalies of this kind, points which do not seem to lie close to a smooth curve If the experiment can be repeated, that should be done, and averaged or best data used. In the present instance, measurement at a few more frequencies between the present lowest and next lowest point would yield intermediate points which would help clarify whether the last point is badly off or not. If the experiment cannot be repeated, then outliers of appreciable magnitude, such as the lowest-frequency point in the present plot, should be omitted (or weighted very low) in subsequent CNLS fitting. 

When large anomalies have been eliminated, it is still often valuable to reduce the remaining smaller deviations (noise, experimental error) from a smooth curve by smoothing. The resulting smoothed data will then generally lead to more 

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Goldring et al. in their treatment of anomalies in extinction coefficient measurements, presented both a report of the precision and accuracy of the Beckman DU and the conditions under which it achieves optimum performance. Caster reported on the variability of this spectrophotometer. 

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