For those unaware, I'm spending a couple of months this summer in Boston working in the much maligned world of quantitative finance. It's alternately mindless and reasonably interesting work. (Though the projects I've been working on so far haven't really exercised my inner mathematician all that much.)

As a native Oregonian, I find sales taxes, such as the one imposed on shoppers in Massachusetts, annoying to say the least. Not so much because I resent paying an extra five or six percent for toothpaste, but rather because retailers don't include the sales tax in the price. As good as I am at mental math, it would just be easier if the price tag on an Apple iPad read $530 instead of $499. It's not exactly rocket science — most shops in Western Europe include the VAT in the price shown to consumers.

So I was pleasantly surprised yesterday when I paid exactly $64 for a pair of $64 shoes at the Puma store on Newbury street. For it turns out that shoppers in Massachusetts don't pay sales tax on clothing or shoes, so long as an individual item costs less than $125.

On face this policy seems a sensible way to skirt the somewhat regressive nature of sales taxes. People who can afford to spend $5,000 on a single suit or dress probably won't be "hurt" as much by a sales tax as people form whom a $40 pair of shoes stretches the budget. For the former group the extra $300 spent on an already expensive article of clothing just means their wine cellar will hold one fewer bottle of Château Margeaux. For the latter group, the extra $2.50 might mean one more dinner from a fast food chain instead of something more interesting and less obesity-inducing.

But it seems to me that this policy could be better implemented, provided the relevant data are available. For instance, some classes of clothing just cost more in general due to factor prices. Even H&M can't sell a tailored jacket for $10. Reasonably nice wool costs more than cheap cotton, and the intricate work of attaching sleeves, a lining and so forth requires more person-hours of labor.

The tax regime really ought to assess tax based on the price of a given article of clothing relative to its peers, so that a $50 pair of socks is taxed, but a $50 pair of shoes is not. A 22-year-old straight out of college would likely be hurt more by paying a sales tax on a few $300 suits he needs for his first job than a 45-year-old lawyer who spends $300 on a pair of cufflinks.

If I have time later today, I'm tempted to download product data from Amazon.com to take a look at the distribution of prices among certain classes of apparel.