How do doctors make predictions of how long someone will live or if they’ll ever walk normally again?

Question

I was rewatching an old video on YouTube and the guy was able to walk again after 10 months of practicing yoga and losing 140 lbs. If no one on earth can exactly predict when someone will die or if they’ll be able to walk again, how and why do doctors come up with these predictions?

https://youtu.be/qX9FSZJu448

In: Mathematics

Answer 1

Analysis of decades of patient data has allowed doctors to give fairly accurate predictions regarding outcomes