Fast and correct, or comprehensive and insightful. (Scroll down to see suggestion)
I do not think that either type of answer is inherently better. A "good enough" answer will solve the problem and get you back on track. An insightful answer will teach you something new, make you more skilled.
The problem is that if you focus only on rewarding fast answers, many of the comprehensive answers will never get posted at all.
As it is now, the quick answers float to the top, and stay there. People do not always bother to check all the answers, and they might not consider the depth of the question, the way the asker would. If a top voted answer is good enough, chances are it will recieve more votes than it deserves, merely because it is voted highest. That is an error of conformity of the reviewing audience.
Unless votes are made in the blind, you are always getting a systematic error. Simply put, here's the three biggest culprits:
- How many upvoted it?
- How high up on the answer page is it?
- Who made the post?
That is: People will tend to conform to the majority's opinion. People will only read answers to a certain thread depth. People will tend to agree with "authorities", e.g. people with high rep, many badges, etc.
These are all basic concepts in psychological testing. There are many kind of errors that prevent you from getting correct answers. Here is a wikipedia entry on bias, take a look at Bandwagon effect and Primacy Effect.
The correct way to do it, is blind tests
Note: This only affects people who:
- Are eligible to vote (due to rep or
- Still hold the option to vote for the
- Are not the person posting the
Anyone who just want to see the voting results can do so by clicking "finished voting".
- The author's name & rep
- Other people's votes are hidden
until you are finished voting.
- Answers are presented in semi-random
(1): A clearly poor answer should be nudged towards the bottom, a clearly good answer should be nudged to the top. Otherwise we are not using the expertise of our users. However, to avoid tainting by position, order is determined by vote intervals, with random order inside the intervals.
Those who do not vote
What about users who are only after answers? If you cannot or choose not to vote on a question, all the information becomes visible to you, and you can use this additional information to evaluate the quality of the answer.
By having users only vote on the merits of an answer, the validity of the vote tally will be maximized. In other words, we will know that the votes cast reflect the quality of the answer.
As it is now, the votes reflect something more than a good answer. Two identical answers may get a completely different score. Not because one person was faster in solving the problem, but because they shoved a foot in the door fastest.
How will this affect quick and dirty answers? It will still allow users to get rep for quick answers, but it will reduce the exponential effect of "being first", and also disperse some of the rep towards those who feel they have something to add, despite not being first to reply.
In short, it will be less of an "all-or-nothing" effect to being first.
Note: Please give feedback in the comments. The feedback so far has really been helpful.