pagination / changing results per page

best practice

[The_Hat]

So I built a little piece of php to make a nice automatically generating pagination for my results pages and want to add a way for the user to change how many are shown per page.. but got a question for the usability gurus here

I am thinking about retaining the results count so I can set the beginning result correctly.. In example.. lets say a user views 10 per page and looks through three pages of results and then decides to change the per page to 20, should I

A. Start the results back to the beginning of the results showing the new number per page
B. Send them to a new page showing results 31 - 50, basically reloading the page they are on with the new preference.
C. Send them to a new page showing them results 41 - 60. setting the new preference as they move off the current result set.

Is it common practice to take what has been seen into consideration when changing the number the user wants to see at one time?

[ergophobe]

I've seen it both ways. I usually find it aggravating to be taken back to the beginning (that's the way some stock photo sites I use work). I've also on occasion seen the abomination implementation: I'm on page 3 and it takes me to page 3, so I was looking at 21-30, and now I'm looking at 201-300.

This is not an expert opinion based on testing or anything like that, just my preference: I would like the page I am currently view to be included in the new result set, by preference as the beginning of that set. That helps me stay oriented and see where I am in relation to where I was.

[alt131]

Another opinion with little actual testing to back it up, but my response is similar to ergophobe's on this.

I don't have a preference for seeing the "current" results after applying the increased results display - I'm fine with moving from 21-30 to 31-50, for example.

Because of the varying implementations (and in the absense of any informing user behaviour) my priority for implementation would be to ensure the "result count" is well positioned and makes it really obvious the user has not been sent back to the beginning of the results.

[The_Hat]

Two perfect answers guys, I appreciate it.

[ergophobe]

Actually, I agree with alt131. On a slow connection, it might be frustrating to have the top results shown again. It depends a bit on what they are. Often, when comparative shopping, I want the current results plus a lot more, but not always.

I think alt131 is correct in distilling it down to one feature: make sure the user knows where he is relative to where he was. That, I think is the key.