Equipment with very high accuracy and precision

You could obtain measuring equipment with very high accuracy and precision. You used it to make a sequence of measurements directly at a production process output and depicted the results on the following control chart.

Kindly explain the why the ans MUST be A and not B.

(Pls check attached)



But, looking at the data it looks to me the points are within control limits so it would have been: high Accuracy and may be low precision. But the answer is opposite. Please explain.

PMBOK pg. 190. "Precision means the values of repeated measurements are clustered and have little scatter. Accuracy means that the measured value is very close to the true value"

Here, the points are not very clustered but are very close to the true value i.e. mean. So process is low precision and high accuracy. Not sure about the other half of the answer - whether process should be improved or adjusted. Mostly likely adjusted?

I agree with your explanation but the answer is opposite which is: High precision and low accuracy.

The problem with all these questions is that the source never provides well defined explanation, leaving it to the imagination of the learner to decipher the correct answer. Perhaps, we should wait for someone more experiences to guide us here. 

crushPMP's picture

Even if I understand the part where it's high precision, but low accuracy, I really don't get why the process needs to be adjusted???

I thought the measurements are well within the Upper Control Limit and Lower Control Limit and there is definitely no need for adjustment here!

I just solved the OL's 175 and went with B as the answer and got it wrong. Sorry for bumping the old thread, as we need to settle this for good.

I think that the first answer is true because:
1- if you get the actual mean of the measurements it is differ from the goal (x ) so accuracy is low and need to adjust.
2- little scatter of measurements about actual mean so precision is high
3- all measurements within specification limits but not within control limits (PMBOK® Guide 4th Edition, page 206).

Equipment has some high accuracy among the precision to read data or make parties to get on it with their paths. Material that has some facts to read has to take myassignmenthelp this can used to get the partition to have the access or need to over base on it.