"How Many Economists Does It Take To Change A Light Bulb?" joke

How many economists does it take to change a light bulb?

None. If it really needed changing, market forces would have caused it to happen.

None. If the government would just leave it alone, it would screw itself in.

None. The invisible hand does it.

Two. One to assume the existence of ladder and one to change the bulb.

Eight. One to change it and seven to hold everything else constant.

One to prepare the proposal, an econometrician to run the model, one each MS and PhD students to write the theses and dissertations, two more to prepare the journal article (senior authorship not assigned), four to review it, and at least as many to refine the model and replicate the results.