Start here. Then keep reading. It has nothing to do with economics, but a lot to do with statistics.
Or don’t, if you need to get something done this morning.
Update: One reader writes in:
“I beg to differ that this link has nothing to do with economics: The same technique it uses to detect possible making-up of poll numbers was used in a recent paper to detect possible making-up of National Accounts statistics in some developing countries in a widely used economic dataset:
By James Kwak