Historical evidence. Firstly, IE users are less likely to care enough to upgrade a browser, for the same reason they didn't care enough to look for a better one. Namely, it doesn't really matter to them and they're unaware of why it should. Secondly, Microsoft is a lot less pushy about software updates than other browser vendors.
IE7 came out 4 years ago (and then IE8 two years later), but despite what an enormous improvement it was to IE6, we're only now seeing IE6 finally start to fade away. IE6 usage didn't drop below half of all IE usage until around June 2009. By comparison, Firefox 3 had more than double the usage of FF2 within 3 months of its debut. Chrome shows even better (in fact, absurdly fast) adoption rates.
Since those not using Chrome probably don't know about it, it's worth noting that Chrome updates itself whenever you start it. That explains the absurdly fast adoption rate of new versions.
But that still doesn't provide evidence that people buying a new computer are the only non-developers who will get IE9. You need to demonstrate that upgrades from IE6 to 7/8 are non-existent.
In fact, I'd say the fact that IE7 has dropped below IE8 is evidence that people on IE do upgrade, and that the people on IE6 are only on it because they need it.
I'm counting on common sense interpretations here. Obviously it's not the case that there are NO EXAMPLES of 7->8 upgrades. I'm suggesting that it's very much an exception rather than a rule. I don't have the energy to dig up the stats demonstrating a correlation between purchases of new computers and browser version market share. It's probably there, maybe it isn't. Whether that's the cause is immaterial though because the point remains: new IE versions tend to be adopted very slowly.
And I would point out the enthusiastic reception of Win7 (comes with IE8) compared to the chilly reception of Vista (came with IE7) as evidence that browser adoption is correlated with sales of new computers (or more specifically, new OS's. Keep in mind a lot of Vista machines were sold with downgrade packs).
And yes, Chrome auto-updates. That's part of my point about Microsoft being less pushy with their updates than other vendors.
> I'm suggesting that it's very much an exception rather than a rule.
I think the opposite is true. I don't have hard data to back up my thoughts, but the fact that IE8 is above IE7 seems suggestive.
> I don't have the energy to dig up the stats demonstrating a correlation between purchases of new computers and browser version market share. It's probably there, maybe it isn't.
So you're retracting your statement, then? I'm asking because you seemed to lack any sort of doubt when you made it, going to the length of using of course.
> Whether that's the cause is immaterial though because the point remains: new IE versions tend to be adopted very slowly.
I agree (relative to other browsers at least), but this is certainly not what you stated in your original post.
Why so?