Radio Button Best Practices (Answer Limit)

Question

From a "Best Practices" perspective, is it better UX design to ask 1 question with a set of 4 radio buttons, 2 questions with a set of 2 radio buttons each, or is this really just splitting hairs?

To provide some context, a specific scenario would include:

1 Question 4 Radio Button Approach:
Question: Would you like to include graphs in your report?
Answer 1: Yes, and I have some specific indices and medians in mind...
Answer 2: Yes, but just give me the basics...
Answer 3: No, but I would like some specific indices and medians for the performance charts...
Answer 4: No, lets keep it simple. Just the basics for the performance charts...

2 Question 2 Radio Button Approach:
Question 1: Would you like to include graphs in your report?
Answer 1: Yes
Answer 2: No
Question 2: Would you like to choose specific indices or medians for your report?
Answer 1: Yes
Answer 2: No

Answer 1

I like your 2 question, 2 radio button solution as it's easier to look at.

Question 1: Would you like to include graphs in your report?

Question 2: Would you like to choose specific indices or medians for your report?

In this case, however, you could probably adopt checkboxes instead. Yes/No radio buttons are necessary when accuracy is absolutely critical and you want to ensure the user has actually read and understood the question. Such cases might include insurance applications (something I've done quite a bit of), filing your taxes, formatting your hard drive, etc.

But by using checkboxes you could turn it into this...

Please indicate what you would like on your report:

• graphs
• specific indices or medians

Answer 2

While the average reading speed of an english speaking adult is around 200 words per minute, some read at a much slower rate - and it's not necessarly something linked to intelligence. I know one guy with a PhD whose reading speed was just 59 wpm.

Your first approach contains close to 60 words, and would take him almost a minute just to read. That's a long interruption in the workflow of someone trying to get to a specific goal.

For this reason, I'd suggest something like this:

What should be included in your report?
[ ] Charts
[ ] Indices and medians

Sigh. This is much like @Steve Wortham's answer (+1) which appeared while I was writing this. I'll post this anyway, as it gives some motivation for the choice.

Answer 3

I would go with a modified second option, like this:

Question 1: Would you like to include graphs in your report?
Answer 1: Yes
Answer 2: No

[ ] Include indices
[ ] Include medians

In other words: two radios Yes/No, and a set of options that will be grayed out if the user selects the No radio.

I find two serious drawbacks with the first approach: a) it requires more thinking than necessary, and b) it will be very difficult for you in the future to add more options if you want to.