You'll get the best results and statistics if you present a survey.
But....
what exactly is it that you believe about extra-terrestrials
I believe that extra-terrestrial, intelligent entities have been visiting us rather regularly since at least the early 1940's, and likely more
isolated visits even earlier
Reasoning: Prior to this time, the phenomenon didn't really exist. Then, people started seeing saucers. The government took the matter very
seriously, and funded projects Twinkle, Sign, Grudge, and Bluebook over the course of many years to ascertain the threat level posed by the
phenomenon. Many reports are made by military officers, pilots, and other trained observers, and the craft's attributes defy current performance
levels of terrestrial craft. The case of Betty and Barney Hill remains as an excellent piece of evidence supporting visitation.
Do you think they exist at all?
Yes.
Reasoning: The Drake Equation (or even just basic statistics) supports that given the number of stars in the Universe, there are likely a LOT of
intelligent civilizations out there. It furthermore stands to reason that some of these civilizations have been around longer than we have. Given our
current technology development as a curved scale, and applying that to older civilizations, it is not unreasonable to assume they've developed
technology that enables expedient interstellar travel.
Do you think intelligent life has visited earth, and if so do you think the government has actively tried to cover up the fact that this
happened?
Yes.
Reasoning. The government has been caught in the coverup attempts quite regularly. For example, the government's official position has always been
that Blue Book was the last official government interest in the UFO phenomenon. Yet, we have numerous examples of officially-sponsored inquiries after
this, but held more secretively, such as the Robertson Panel. In addition, there is Roswell. Here we have a case where an official press release
stated they recovered a flying disc, and then a weather balloon retraction. Later, we have the government claiming that alien bodies were really
dummies from Project High Dive. Problem: Project High Dive (and it's dummies) didn't exist in 1947.
There is also a paper trail suggesting the formation of a secret group (call it Majestic, MJ-12, MIB or whatever you like) made up of individuals who
would have been ideal for investigating such phenomena... Even former officials in charge, and high up, in Blue Book have gone on record stating the
coverup.
Also, why is it that you either do or don't believe in these things?
See above, as easier to give you the answer to this point by point.
Demographic statistics (also good for your paper).
White Male between 25-40 yrs old, College educated (Bachelor's degree, halfway through Master's (MBA) program), Southeast U.S., Project Manager for
a nationwide Telecommunications company.