Above or below the average height in your country?

[JamesMoulang]

Wouldn't a lot of average based questions make a good 50-50 split, by definition?

[JamesMoulang]

Maybe this doesn't work, at least not with anything related to nationality or sex, because those both affect height.

[mtrimpe]

I'd say this would need to be defined as average for your sex at the time of your birth to be an accurate long-term predictor. You could be above average at 18 but below at 50 for example.