Is the StackExchange model a good one for avoiding duplicate questions on community Q&A sites

Question

Is there any data to support the strategy of suggesting similar questions on community sites involving user-generated questions and answers?

The only example of this strategy I know of is (was?*) on StackExchange. See the screenshot below:

I have assumed that the purpose of the feature is to avoid duplicate questions, so I suppose there are two questions here:

1) Do duplicate questions inhibit the growth of community-driven Q&A sites, and if so, under what conditions / at what scale?

2) Is the strategy of suggesting similar questions to users as they begin the process of creating a new question effective in reducing duplicate questions?

.* This feature is no longer appearing for me, so I'm also wondering if it has been deprecated, or is it only shown up to a certain reputation level?

Answer 1

1. Yes, users waste time to post exist information.

Question and answer boards were designed to contain knowledge to be reused, so it is not make sense that askers do not learn from exist information, and ask questions which are similar to answered questions. Duplicate questions waste time of users who answer questions. Users should create new knowledge instead of answering same question for many times.

1. It may be help to decrease duplicate question, but it have to use with another techniques.

The system shows similar questions to asker, it assists users to search answers that users need. If users see questions which have solution that can solve their problems, they will not ask questions, since they get what they want. Thus, the suggest question may decrease duplicate questions.

However, Stackoverflow does not rely on this function alone. Stackoverflow created culture that duplicate questions are undesirable. Users can give penalties to askers who ask duplicate questions by voting down or deducting reputation points.(It happened to me many times.) Thus, users will search questions carefully before ask questions, because they do not want to be punished.

In additional, the system reminds users before asking question to search for similar questions first to make users' mental model that duplicate questions are not good.