What are the limitations of patent mapping and patent statistics?

Simply counting patents is often not enough, since their value can differ greatly from case to case. What you need to do is assess the importance of the inventions concerned based on significant indicators such as patent family size, the length of time the patent has been in force and citation information.

You should always compare the resulting information with other sources, such as market information and expert opinions. And it helps to be familiar with the patent grant procedure.