You're asking me for stats about a statistically non-existent problem you made up. How many article get changed after they get posted and this isn't brought up in the comments?

Also, sometimes articles get changed because authors respond to HN feedback. Interaction between authors and the community is one of the valuable things about the forum. There's no added value to discussing some frozen snapshot of a web page - its a web forum for talking about web links rather than some revision control system.

What type of information?

The domain, for one thing.