In the US right now there is a major scandal going on in the Veterans Administration where allegedly appointments were falsified to improve managerial metrics. This is not unique to the VA, it is probably happening in every organization.
There is a major US department store chain that has a package pickup model where you scan your receipt and, on a huge monitor mounted on the wall you can track your package"s process as it is delivered to you. Over the space of several years, each time I picked up a package at different stores, I would watch as the monitor reported that my package had been delivered to me in X minutes, yet it still took another 5-10 minutes for me to actually receive it. Like the VA, store level employees were gaming the system.I'm sure someone back in corporate was noting the short delivery time on their dashboards yet the reality was the true metric was probably close to double the gamed one.
We could all probably think of other examples, so I'll stop here and get right to the bottom line at the bottom.
If you are a manager and you are relying on metrics such as these to measure performance especially when incentives are involved, you may want to verify your data. As former president Reagan said, "Trust, but verify."