Perhaps a better statement of the example might be: "No NC's for which cause determination identifies personnel-error as a contributing factor".
Actually, thinking about this more, this objective still might not reflect on the effectiveness of training.
For example a training program for receiving might just be simply to follow the instruction: "visually inspect the item and confirm it is blue".
The employee, trained on this, might do EXACTLY what the training intended, but pass a damaged item (because the only thing they are checking for is its colour).
In this case, is the training effective?
On the one hand it is, because the employee is doing precisely what the training program prescribes.
But on the other hand, the training program is clearly insufficient to prevent NCs.