Share your expertise and teach me the antonym for 'wild guess'?

Usually I understand your questions .... sometimes I just do not :/  but my favourite song now  is about wild horses... no a guess ..but I tried :) 

https://youtu.be/6I0hXe0cMUM

Calm knowing

Untamed birds?

Oh, wait, you said 'wild guess', not 'wild geese'.

Untamed assumption?

Edit again:
You said antonym not synonym. I am at a loss, sorry. This post was edited by texasescimo at July 19, 2017 6:03 PM MDT

There is none in the English language.  I looked it up according to Thesaurus as well as Urban Dictionary.   You will have to invent the antonym for 'wild guess' yourself. 
Might win a Nobel prize.

I'll try a wild guess: 'what the x-ray shows'. This post was edited by Kittigate at July 19, 2017 6:04 PM MDT

Theorize. 

cant since im not an expert on it

Relaxed and deliberate knowledge. This post was edited by Harry at July 19, 2017 11:47 PM MDT