The crackpot index is a number that rates scientific claims or the individuals that make them, in conjunction with a method for computing that number. The method, proposed (most likely as a joke) by mathematical physicist John Baez in 1992, computes an index by responses to a list of 37 questions, each positive response contributing a point value ranging from 1 to 50. The computation is initialized with a value of −5.
Presumably any positive value of the index indicates crankiness.
Chris Caldwell's Prime Pages has a version adapted to prime number research[1] which is a field with many famous unsolved problems that are easy to understand for amateur mathematicians.