Thesis statements (APA) 1
Example:

Believers in so-called alien abductions think that extraterrestrials have contacted humans, but a better explanation for such experiences is the phenomenon known as sleep paralysis.

At least several hundred Americans—and perhaps many more—believe that they have been attacked in their beds by extraterrestrial beings.

The first sentence states an interpretation that can be developed in a five- to ten-page paper. The second sentence merely states a fact.