but if the sample set size from flickr is large enough (for example their entire userbase)I think this is the problem: for the sample to have any validity at all it needs to be a representative sample. The point I'm making is that, regardless of size, there's insufficient information in Flickr's data collection to infer beyond the Flickr user base.
So whilst all of the above issues you mention may be in flickr numbers, there is no way to account for them specifically and similarly there is no reason to expect that they would favour or disadvantage
More importantly, though, there's no reason to believe they wouldn't.
Oh come on and quit with the conspiracy garbage will you?
In order for a statistical sample to be valid, you have to be demonstrably confident that it isn't skewed. While the Flickr survey is interesting for what it is, it simply doesn't contain enough data, and there are too many confounding factors to allow me to exclude the risk of bias to use it to infer camera ownership and/or recent purchase.
Would you like to qualify your statements about bias risk?
And let me pose some questions for you...
- how would flickr introduce bias?
- what does flickr have to benefit from bias?
- what outcome would flickr see as a result of it being biased?
In essence, if flickr were going to introduce bias and from where I sit, I can't see any reason why flickr would benefit from bias in any of the numbers presented here.
If I were flickr and I was looking to produce biased numbers then I'd want them to make it seem like flickr was improving and growing and being better. I'd want to promote something like "2013 5.4 million active users, 2014 6.1 million active users" or some such. That sort of reporting benefits flickr in a very direct way. Reporting on the % breakdown of manufacturers doesn't really benefit flickr at all.
But that's just me. Maybe I'm special because I don't see flickr as being out to get me or Canon or Sony. flickr competes with the likes of picasa and so forth.