from Hacker News

Introduction to the concept of likelihood and its applications (2018)

by sebg on 10/23/25, 10:52 PM with 8 comments

• by pkoird on 10/24/25, 12:35 AM

  Perhaps it was due to English not being my primary language, but it took me an embarrassing amount of time to learn that probability and likelihood are different concepts. Concretely, we talk about probability of observing a data given an underlying assumption (model) is true while we talk about the likelihood of the model being true given we observe some data.

• by WaitWaitWha on 10/24/25, 4:50 PM

  The way I read this (and my layman understading) probability is about predicting future events, given a known model or assumption, while likelihood is almost the mirror image: I observe the data/outcome, and I ask: given that data, how plausible is a certain model or parameter value?

  Another way of looking at it:

  probability: parameter/model is fixed; outcome is random/unknown.

  likelihood: outcome/data is fixed; we vary the parameter/model to assess how well it explains the data.