ideal chart, the variation in the parts should be large, in comparison to the variation in the readings around the average for each part. this means that the parts are quite different from one another, while the measurement is taking readings very close to the part average. if the individual points are spread out from each other on each sample, then it means the measurement system is having a hard time picking up whether the variation is coming from the part or the measurement system itself.
the next chart (middle right) shows the differences between operators using their overall average reading. a good measurement system would not allow operators to cause 