That's why people buy a "pint" of ice cream that is really 14 ounces; it may be the same-sized container with more air in the product, or it might just be fancy new packaging that is a tad smaller. The issue is that the manufacturer sets up the unit price in ounces, where the competitor selling a true pint does its unit pricing by the pint. That makes it hard for the average consumer to do a quick-look price comparison and know which is the better deal.

The same thing goes for paper towels and toilet paper, where the unit can be the feet of toweling you buy or it can be "sheets," a unit for which there is no standard measure. Cut the sheets smaller but take a few feet of length off the roll, and you can still have more sheets -- but less product -- for the same money.

A few slices out of a package of cheese, one less hot dog in the pack or an ounce less of deli meat -- all changes the makers are hoping most consumers won't notice so they will stick with the brand rather than shop based on price and value.

Measure for measure

This is not a new problem. I don't know who decided that a coffee cup would hold 6 ounces when we were all taught in school that a "cup" is 8 ounces, but check any china set and you'll see the difference.

At some point, the units of measure became units of packaging, where consumers ask for a "pound of coffee" but don't recognize that the package holds just 12 ounces.

I'm guilty of this myself. I'm tired of having to tell people how much weight I have lost since my heart attack last fall (it's a lot, but I have much more to go). I simply tell people that I have lost "one chin," putting me halfway to my goal of losing "two chins." How many pounds are in a chin? I'm not telling; but I won't be surprised if someone starts selling super-sized bulk-food packages and tries to say they are a chin's worth rather than making it easy for the consumer to figure out.

As consumers, we can hope federal regulators will improve the measurement standards, making it easier for shoppers to do their due diligence. If they can't define a "sheet" for toilet paper or paper toweling, they could at least require that unit prices for those products be shown by the square foot.

Even if consumer watchdogs do create uniform standards, consumers still need to watch for product deflation, because it is a form of price inflation. While people may feel as if they are staying within their budget, what matters ultimately is that they get sufficient value for those dollars.

"The consumer is slowly being duped," MacGregor said. "Products are thinner, smaller, the package has an ounce or two less than it did six months ago, but the average consumer doesn't really notice it because the bottles and packages are all different sizes or are shaped to feel the same. Then you have the manufacturers playing games with unit pricing, and it puts the average consumer at a disadvantage."