Is the downvote-answer feature necessary on Quora?

Yes.  Without downvoting, I think you open Quora up to non-constructive answers which weaken the strength of the site. See What are good and bad reasons to downvote answers on Quora? That question has a number of answers that get at this point. That question and its answers also support the secondary point that Justin Bishop is making — which I agree with — that unfair/unreasonable downvoting is demoralizing.

How do I invite people to Quora?

For both Gmail and Yahoo, Quora uses OAuth [1][2] to request authorization to access a user's email contacts.  If you're not familiar with OAuth, what this means is that Quora never actually handles the user's password.  Instead, the user is directed to either a Gmail- or Yahoo-hosted authorization webpage where the user logs in and grants access to a third-party application (in this case, Quora); the application then gets a short-lived, authorized request token with which to make API calls for the user's data.  Both Gmail and Yahoo expire their OAuth request tokens after an hour.  Using OAuth protects the user's password and also restricts third-party API access by Quora to only the users' contacts data.

Even for other email providers where the public OAuth standard is not supported, we value our users' privacy and security and do not save passwords.

[1] http://code.google.com/apis/acco…
[2] http://developer.yahoo.com/oauth/

How can I anonymously add content on Quora?

Anonymity on Quora can only be used to anonymously add questions or answers. To learn how to anonymously ask a question or write an answer on Quora, see the answers to these questions:

  • How do I ask an anonymous question?
  • How do I write an anonymous answer on Quora?

For more information about anonymity on Quora, check out:

  • How does anonymity on Quora work?
  • How secure is the anonymous option on Quora?
  • How does Ask to Answer work with anonymity?
  • What actions am I not able to take anonymously?

How many questions are asked on Quora each day?

I definitely cannot give you the current statistics but here is a snapshot of the last known.

Total number of Questions:4,203,554 questions as of June 1st, 2015 (12:25 utc).
Source: How many questions are on Quora? (answered or not)

Approximately ~5593.7 questions daily. (Dec,2014)

Assuming a good 6000+ questions to be the daily rate today; it is safe to assume that 70% questions don't show up on everyone's feed. At most you can get 30% of the questions on your feed in a whole day.
Taking into account that you refresh 2-3 times in a minute.

There is no official Quora policy towards unanswered questions but yes if a question doesn't attract anyone to answer the question or want answers to it then it is gradually marked as needs clarification. Then, most probably it goes into moderation timeline; which is where it is decided to keep the question or remove it. This is a pure binary call taken by the moderation in higher levels and the machine in lower levels.

NB:
 The numbers and figures quoted are subject to:

  1. Time of day
  2. Traffic density
  3. Refresh rate
  4. Global topics/ trending issues

and other sensitive factors.

I say again there is no way to determine an exact figure to a real-time system. However, approximations can be made.


Originally Answered on: How many questions on Quora go unanswered? What is Quora's policy towards them?

How will Quora use game mechanics to get lots of high quality user contributions?

I think Quora could benefit from using game mechanics. Consider if you were ranked globally and against your friends in these categories:
Number of upvotes
Number of answers that are the most up voted for a question
Number of questions asked with at least one answer
Number of questions answered
And many more…

That would clearly incentivize users to ask more question and answer open questions. Quora's biggest problem in my eyes is that I have had several questions sitting open in my Answer section since I joined, and simply no one wants to bother to answer them.  Think about if Quora gave you rankings on topics, like if I get 10 endorsements for the World Cup and I now have a title on any question that I answer regarding the world cup.  Think of this like badges in foursquare, they are basically ornamental but show my overall usage of the product.  Quora is really close to using obvious game mechanics.

Eston is right that Quora gets around this now because users are not anonymous, they want to show how smart they are to their real friends, but that does not mean they couldn't get some mileage out of game mechanics.