Four

hundred voters participated in the survey. How can we

claim to know the opinions of all Fayette County voters

based on only 400 interviews?

The answer

is that we don't know exactly, but the process of

"sampling" lets us make a pretty good estimate.

Sampling sounds fancy but we do it all the time. For

example, we decide whether or not to add salt to a pot of

soup based on a small sample - a single spoonful.

Because that spoonful of soup needs to be

"representative" of the entire pot, we stir the

pot before taking our sample. That gives us a random

sample of the soup.

The fact

that we surveyed a random sample of Fayette County voters

is important, because it is the randomness of the

sampling that allows us to claim that our poll is

"representative."

Even with

what seems like a small sample of 400 voters, we are able

to make a surprisingly accurate estimate of the attitudes

of all voters. How accurate a poll is can be judged by

its "margin of error." In the case of our

study, the margin of error is plus or minus 5 percent at

a 95 percent confidence level.

What this

means is that if we conducted our study 100 times,

surveying 400 voters each time, 95 of those studies would

give us results within five points of the true number.

This, combined with the fact that we have had strikingly

similar results when conducting the same poll in

neighboring counties, allows us to be quite confident

that the survey results we reported accurately reflect

the attitudes and opinions of Fayette voters.

Beth S.

Schapiro, Ph.D.

President

Beth

Schapiro & Associates