E. Systematic Errors

1. Causes

Systematic errors are generally the result of equipment maladjustment or its reaction to environmental condition changes. For example, a steel tape changes length based on temperature. We can compute a correction as long as we know the steel’s physical characteristics, a calibration temperature and length, and the temperature at measurement.

Systematic errors originating from equipment condition can be resolved by procedure or adjustment. Specific compensatory procedures are described in chapters and sections on instrument use. Topic IV. Equipment Checks and Adjustments describe mechanical compensation for different instruments.

The presence of systematic errors can lead to a measurement set which is precise but not accurate. Recall the Precise but not accurate shot group from before, Figure E-1.

Figure E-1 Systematic error effects

While the shot group is precise, something is consistently happening which prevents hitting the bull's-eye. The shooter is apparently using correct  procedures, but the maladjusted sights on his gun are affecting his results.