How to A/B test caption length the honest way

How to A/B test caption length the honest way

"Long captions boost watch time, people read them." Maybe. Most repeat it without a control. Build one:

— Take 8 comparable videos. 4 get one-line captions, 4 get 3-4 sentences.
— Same content, same hook, alternate post days.
— Compare avg watch time and the 'watched full' rate.

The mechanism people forget: a long caption can add seconds of 'watch time' from reading while the video loops — inflating the metric without real interest. So check shares and saves too, not just watch time. If saves don't move, you bought a vanity number. Test the outcome, not the proxy.