Regards,
Bill Hooper
====================
Begin forwarded message:
From: Bill Hooper <[EMAIL PROTECTED]>
Date: 2004 July 18 2:11:36 PM EDT
To: [EMAIL PROTECTED]
Subject: "Ounces and Pounds Foolish"
Ms. Pressler,
I appreciate the comments you made in your "Ounces and Pounds Foolish" article. It is indeed difficult to compare unit prices when one item is priced by cost per ounce while another is priced by cost per pound, etc. The difficulty is caused primarily by the old English measuring units that are used. If metric units of measure were used there would be virtually no problem at all. It is still preferably, as you contend in your article, to have all unit prices for products of the same type listed expressed in the same unit, whether metric or old English, but to the extent that they aren't, metric measures would make things a lot easier.
As an example, if unit prices were in metric, it wouldn't matter much if one item was priced in cost per gram while the other was priced in cost per kilogram.* Since a kilogram is just 1000 grams, it is easy to convert mentally from one unit price to the other. Something that costs $3.79 per kilogram would be 0.379 cents per gram. (Since grams are quite a bit smaller than kilograms, it makes sense to convert the price from dollars to cents also. This step is so easy that most of us don't even have to stop to think that we are multiplying by 100 to convert $3.79 to 379 cents.) It is convenient to avoid very small decimal fractions by converting to cents first. That gives a unit price of 379 cents per kilogram, then just divide that by 1000 grams per kilogram to get the final result of 0.379 cents per gram.
Although the above arithmetic is simple, I think shoppers would very quickly see the pattern; namely, that one may simply move the decimal point one place to the left to get the final answer. Once that is learned, all further conversion of this type would be almost automatic.
If one had to do that in pounds and ounces, it would be harder. I'll use $1.72 per pound since that is equivalent to the $3.79 per kilogram used above. The equivalent arithmetic would be: convert the price of $1.72 per pound to cents, getting 172 cents per pound, then divide by 16 ounce per pound to get 10.75 cents per ounce. The only difference is that the kilogram to gram conversion requires an easy division by 1000 where the pound to ounce conversion required the more difficult division by 16. But when it comes to convenience, that's a big difference. Most of us can divide by 1000 in our head. Few of us want to (or can) divide by 16 without a calculator.
Converting unit prices by the litre or by the millilitre would also be much easier than by the quart, gallon or fluid ounce. It is especially easier since there are THREE different old English units to contend with. And that's sometimes further complicated when the contents are reported in a mixture, such as "2 qt. 3.6 fl. oz.", something that is NEVER done in metric. It's also easy when things are sold by length so that conversion would be between metres, centimetres and millimetre which are related by factors of 10, 100 and 1000, rather than inches, feet and yards which are related by factors of 3, 12 and 36.
Metric pricing generally would be a boon to comparison shoppers. I hope you agree.
Regards,
William Hooper
*PS
In much of Europe, many foods are sold in multiples of 100 grams. Therefore they are priced per 100 grams. Unit prices can be expressed in dollars (or euros, etc.) per 100 grams just as easily as per kilogram or per gram. And any necessary conversion from one form to the other is just as easy.
