All polls are psychological...

[kentuck]

and intentionally so...If they report one candidate is far ahead of another, the psychological effect is to lower the turnout for the candidate that is ahead and to strengthen the candidate behind. If they report that the two candidates are in a deadheat, within the margin of error, the psychological effect is to create a momentum for one candidate or the other, thus indicating more interest in one over the other.

All polls are psychologically manipulative until the last few days of a race. Then they attempt to be accurate to save their credibility for the next election cycle. As you will notice, polls will swing wildly from one day to the next, according to the interest of the pollsters. No policy decisions should ever be made from poll results and neither should political opinions.