On most websites or blogs, the ratio of readers to commenters is gigantic. On this blog, a post that garners 40 or 50 comments is considered quite a bit, even though there are many thousands of readers. The stream of comments can take many shapes, depending on the nature of the post. And, once again depending on the nature of the post, the commenters here can seem like a fairly diverse lot. But lately I got to thinking: what kind of person comments on a blog, and why?

I like blogs as much as the next guy, but I don’t think I’ve ever left behind a comment, even though I have plenty to say about lots of things. So what distinguishes me from a blog commenter?

I realize there is a selection problem here: anyone who responds to my question about why commenters comment is, alas, a commenter. Which means that regular commenters will be overrepresented in the comments — unless, of course, a whole bunch of you who never comment decide to go ahead and log in and, in the comments section, tell us why you never comment. Or why other people do.

Comments welcome.

Several weeks ago, I was talking to a physician in Houston, the sort of older gentleman family doctor you don’t see much of anymore. His name is Cyril Wolf. He’s originally from South Africa, but other than that, he struck me as the quintessential American general practitioner of decades past.

I’d asked him a variety of questions — what’s changed in recent years in his practice, how managed care has affected him, etc. — when suddenly his eyes fired up, his jaw set tight, and his voice took on a tone of great exasperation. He began to describe a simple but huge problem in his practice: a lot of generic medications are still too expensive for his patients to afford. Many of his patients, he explained, must pay for their drugs out-of-pocket, and yet even the generic drugs at pharmacy chains like Walgreens, Eckerd, and CVS could cost them dearly.

So Wolf began snooping around and found that two chains, Costco and Sam’s Club, sold generics at prices far, far below the other chains. Even once you factor in the cost of buying a membership at Costco and Sam’s Club, the price differences were astounding. Here are the prices he found at Houston stores for 90 tablets of generic Prozac:

Walgreens: $117

Eckerd: $115

CVS: $115

Sam’s Club: $15

Costco: $12

Those aren’t typos. Walgreens charges $117 for a bottle of the same pills for which Costco charges $12.

I was skeptical at first. Why on earth, I asked Wolf, would anyone in his right mind fill his generic prescription at Walgreen’s instead of Costco?

His answer: if a retiree is used to filling his prescriptions at Walgreens, that’s where he fills his prescriptions — and he assumes that the price of a generic drug (or, perhaps, any drug) is pretty much the same at any pharmacy. Talk about information asymmetry; talk about price discrimination.

I had meant to blog about this, and had collected a few relevant links: a TV news report in Houston about Wolf’s discovery; an extensive price comparison compiled by a TV news reporter in Detroit; a Consumer Reports survey; and a research report on the subject from Senator Dianne Feinstein.

But I had forgotten all about this issue until reading this comprehensive article in yesterday’s Wall Street Journal, which does a good job of measuring the difference in prices between chains (most of the differences aren’t as drastic as Wolf’s example with prescription Prozac, but they are still huge) as well as the economics behind the pricing of prescription drugs in general. Perhaps the most interesting sentence in the article is this one:

After a call from a reporter, CVS said it would drop its simvastatin price [from $108.99] to $79.99, as part of an “ongoing price analysis.”

So that’s what they call it: “ongoing price analysis.” I’ll have to remember that the next time my kids catch me trying to buy a $2 toy when I’d promised one for $20.