National analysts say that when a Wal-Mart Supercenter opens in an area, prices at other supermarkets drop an average of 12 percent.

The Bangor Daily News wants to find out whether that will be true for the Bangor-Brewer area.

On June 18, Wal-Mart opened a Supercenter in Brewer, and the next day, several NEWS staffers headed to the Supercenter, Hannaford and Shaw’s with a shopping list that at the time included 60 items commonly used.

Subsequent trips occurred on July 2, two days before the Fourth of July holiday weekend, and July 17.

The list included brand-name products, except for meat and produce, and represented a wide range of manufacturers. The prices recorded were the best each store was offering on the day we were there, such as grand-opening specials, “rewards” loyalty-card promotions, advertised or in-store specials, and “everyday low prices.”

No manufacturers’ or store discount coupons were used. If products were priced “four for $3” or “two for $5,” we computed the price for one item.

One thing we learned is that comparative shopping can be difficult. Our list of 60 items eventually became a list of 43 items for a number of reasons, such as the three stores did not carry the same sizes of the same brand-name products or one of the stores was out of an item on a day we shopped. For example, Brawny paper towels, Scott toilet paper, Dawn dish detergent and carrots come in packages of varying sizes at the three stores.

We also saw stores compete for Kraft Macaroni and Cheese Dinner eaters. Before June 18, “the blue box” typically sold for 99 cents. Then it was priced at 89 cents at Shaw’s days after the Supercenter opened and 69 cents at Hannaford. It was priced at 60 cents at Wal-Mart. A couple of weeks later, it was “two for $1” at Hannaford, and eventually was priced at 69 cents a box.

Will it stay at 60 to 69 cents a box?

The Bangor Daily News will return to the stores periodically, carrying the same shopping list, to compare prices in our efforts to discover whether the analysts are correct.

We’ll keep you posted.

NEWS intern Jennifer Gunderson helped shop and compute the numbers, and interns Aimee Dolloff, Amanda Dumond, Jackie Farwell and Nancy Jacobson assisted with the shopping.