Which is more usable, outputting dates relative to now or relative to the main action's point in time?

Question

I was just reading the "Open Letter to Joel and Jeff" and I noticed the dates on the comments are relative to when the blog entry was posted. So that means the first entry will always stay as "12 minutes later" and the next will always be "14 minutes later".

From a usability standpoint, does it make more sense to list out times relative to now, or to when the main action occurred?

Upon first seeing this I thought it was a little confusing (I think because I wasn't expecting this), but it very quickly grew on me.

Answer 1

Like most things, the only real answer is, "it depends". When considering lists of dependent comments where each comment must have context to other surrounding comments, relative times might make sense.

However, when showing ATM withdrawl transactions on your bank statement, each item stands alone and relative times might not be the best way to indicate to the reader exactly when the transaction occurred.

Answer 2

I think it depends on the context. If the point of reference is the blog article, then I think it makes total sense to display the time of comments related to that article as happening after the article.

If the point of reference is unclear, it would make more sense to use "now" as a reference.

Answer 3

As Steve Krug recommends in Don't Make Me Think, get rid of the question marks that pop in the user's head when they come to your site. If it is confusing it isn't likely to be helpful.

Although an interesting concept, in this context I think it is more confusing than useful. If I see "answered 18 mins ago" and "answered 17 mins ago" I have a perfect frame of reference. Also this is something I see on many other sites so it does not require me to learn anything new.

On the other hand if I see two comments that contain "5 mins later" and "6 mins later" I don't have a clear frame of reference. The first might be after the original question, but the other? Is it 6 minutes after that previous comment? Or 6 minutes after the original question, thus one minute after the other comment? Finally, this isn't what you typically see on a site so there will be a moment of "huh?" follow by either "wtf?" or "cool!". Not a reaction that should be left to chance.

Answer 4

You left out the option of specifying absolute date and time, which is the one I prefer.

E.g., here on Stack Overflow I always have to calculate how many hours have passed since the last time I checked for new answers so I know how far to go back.