... This isn’t the first time the R-J, which uses Washington-based Mason-Dixon Polling & Research, has published polls that ran far afield of Election Day results. And, the results always seem to skew Republican.

In 2008, the R-J’s final poll had Barack Obama beating John McCain in Nevada by 4 percentage points. Obama won by 12.5. A late poll in 2004 had President George W. Bush beating Sen. John Kerry by 10. Bush won by 3.

The R-J and its pollster were criticized in October 2008 when it polled in two of Nevada’s congressional races, using fewer than 300 respondents in each race. A polling expert with Pew Research Center said he had never seen published polls with such small sample sizes. Polls with fewer respondents are cheaper to conduct, but also mean a greater margin of error.

These polls can matter because, as one Democratic operative complained, they can have the effect of self-fulfilling prophecy, depressing campaign donors and volunteers and infusing Democratic voters with apathy.

...Republican operatives snicker with some glee at the R-J polls, which can provide a lift by energizing donors and volunteers.

As for the polls’ accuracy, however, one Republican operative was blunt. Campaigns pay good money for good data. As for Mason-Dixon polling, he said: “I wouldn’t pay for them.”