Processes may have a problem of Low Accuracy and/or Low Precision. The processes and their associated measurements need to have High Precision and High Accuracy in order produce the expected business outcomes.
Accuracy vs Precision
As we see in the above picture on the top-left corner, all the darts are concentrated in one corner of the board instead of being concentrated at the center of the dart board. This is an example of High Precision and Low Accuracy. Processes which have high precision and low accuracy need to work towards improving their accuracy so that they start achieving the target.
Similarly, the picture on the top-right corner indicates that all the darts are around the internal blue line of the dart-board but are not exactly on target. This is an example of a situation with High Accuracy and Low Precision. Processes with High Accuracy and Low Precision need to focus on improving their precision so that they start achieving the target.