Remove the self-selection bias from Q&A sessions
I've been in quite a few painful Q&A sessions. I think we can do better.
When somebody volunteers to ask a question, their question is not necessarily of interest to anybody in the audience other than themselves. Despite that possibility, publicly answering the question necessarily takes up the time of every person in the audience. Remember the kid in class who asked 90% of the questions — questions that nobody else ever cared about?
There's a simple way to fix this.
Step 1: At the end of your presentation, ask for a show of hands for those people interested in having a Q&A session. If very few people raise their hands, you should be worried about the quality your presentation. However, in the less gloomy scenario where a good number of people raise their hands, you have a representative sample for the audience population that might be interested in the answer to any given question. (The other people should probably leave, but suggesting that would be rude.)
Step 2: After each person volunteers to ask a question, give the audience a quick poll by saying, "Raise your hand if you're interested in the answer to this question." If very few hands go up, reassure the person that their question is a good one [*] and tell them you'd love to stick around and chat afterwards.
That's it. Each several-minute irrelevant Q&A iteration is now reduced to a few seconds and you have additional feedback as to the topics the audience is interested in — the added audience involvement can't hurt either.
Real-time feedback software that the audience interacts with during your presentation can definitely do better. This is just a low-tech proposal to raise the bar a bit.
As my friend pointed out in discussing this, there's no simple way to determine the critical mass for answering a question — it's possible that any given question will only be interesting to a fraction of the audience. It's also possible that you, the presenter, know that the answer to a question is particularly interesting and should be answered without soliciting audience feedback. I believe in your intuition!
Even if it's not — otherwise, question-asking potentially becomes public humiliation, which is very undesirable.