Millions will tune in this weekend to see the Green Bay Packers take on the Pittsburgh Steelers in Super Bowl XLV at Cowboys Stadium in Arlington, Texas. But between plays viewers will watch some of the most anticipated commercials of the year. Andy Rohm, a professor of marketing at Northeastern University, discusses the costly, yet entertaining, advertisements.

What is the average cost of a single ad? Why do these companies feel the expense is worth it?

The average cost for a 30-second ad at this year’s Super Bowl is approximately $2.8 million to $3 million. The FOX network sets the high price in part to offset the cost of securing exclusive rights from the NFL to air the game. The network will recoup $200 million in advertising revenue from the 55 to 60 minutes worth of commercials during the Super Bowl, and additional funds from commercial spots aired before and after the game.

Companies tend to rationalize the expense to air commercials on the Super Bowl because it is estimated that some 100 million to 110 million people will tune in this year — in fact, it is the most-watched televised event in the United States.

The Super Bowl is a great platform for companies to launch new products. Additionally, it is the only televised event when ads aren’t seen as intrusive by viewers — depending on the closeness of the game, many of us will actually tune in more to the commercials being aired than to the game itself.

How do these ads impact sales or a company’s bottom line?

It is often difficult to attribute sales of a product directly to its presence during the Super Bowl, but there are a few ways in which companies try to measure the direct impact of their commercial investment, including Web site and social media traffic. For example, if a commercial urges viewers to check out their site, the advertiser can analyze Web traffic and activity and compare it to the average number of visitors and downloads. The company could also try to drive viewers to its Facebook page or monitor traffic on Twitter.

Because TV commercials are by nature fleeting — they’re on for 30 seconds, then they’re gone — Super Bowl ads tend to be talked about and replayed for days after the game. As a result, Super Bowl advertising offers companies an effective way to prolong their relationship with their consumers over time.

What qualities make for a good ad?

A good ad tries to capture the attention of the viewers by spurring emotions or entertaining us by making us laugh. In recent years, slapstick humor, cute animals, talking babies and the use of well-known celebrities have worked.

Effective Super Bowl commercials are ones developed specifically for the big game. We have high hopes for the new spots, so the pressure is on advertisers and their brands to exceed our expectations. This year, there will be several auto brands advertised, as well as those from the requisite beer and soft drink companies. Because advertisers will try to minimize their risk, we will most likely see some of the same themes that have worked in the past.