W. JOSEPH CAMPBELL: Some midterm polls were on-target — but finding which pollsters and poll aggregators to believe can be challenging.

Forecasts posted at Silver’s FiveThirtyEight.com diverged from outcomes somewhat less markedly than those of RealClearPolitics — but still anticipated closer Senate races than what transpired in Colorado, New Hampshire and Pennsylvania.

Expectations that Republicans would score sweeping victories no doubt were buoyed by the predictions of RealClearPolitics. It projected that the GOP stood to gain three Senate seats and control the upper house by 53 seats to 47 — an outcome that proved illusory.

While hedged, the final, so-called “Deluxe” forecast posted at Silver’s FiveThirtyEight.com and updated on Election Day did little to dampen expectations of a GOP wave. The forecast said Republicans had a 59% chance of winning control of the Senate.

“To be blunt,” Silver wrote, “59 percent is enough of an edge that if you offered to let me bet on Republicans at even money, I’d take it.”

In other words: Don’t Expect Pollsters to Break Their Losing Streak.