Conditional Probabilities

Conditional probability is a central idea, where we compute the probability of an event "A" occurring given that we also have information about an event "B" occurring. For example, if I roll a fair dice, event "A" might be that I roll a 6 and event "B" might be that I roll higher than a 3. If someone tells me that "B" definitely occurred, then it changes the probability of "A", now that I know that "B" is true. This will be a fundamental concept when we develop Bayesian statistics.

This video was produced at the University of Washington, and we acknowledge funding support from the Boeing Company

%%% CHAPTERS %%%
00:00 Intro
01:56 Defining P(A|B)
04:52 Example: Dice
06:37 Example: Cards
08:42 Example: Cancer Screening
11:19 Inference & Outro

[kl-wastikc]

Great video Steve. Where to get a similar board?

[Myexpectationsarerealistic]

For these problems we use Hypergeometric Probability.

This was a Computational problem we had to resolve in card games like twenty years ago.

[adekoyasamuel]

Can someone explain 10:55 on why it is 0.9

[MG-ytom]

P(A|C) Knowing C increase the probability of A. If C is not known the probability of A is 1/6 while if I know C happened the probability of A is 1/5

[konstantint]

Dividing by probability is not obvious, should be explained better imho.

[Loots]

10:17 "Lets say that the test result being positive OR negative is event A" Everyone tested either positive OR negative, so p(A) = 1

[richardedward]

the last 3 minutes was a bit rushed for me. looking forward to part 2.

[lm]

11:05 "So this is a 90% specific test." That is strictly not correct. Specificity refers to P(negative test given no cancer). You are talking about P(positive test given cancer) which is called sensitivity. In other words, a test that picks up 90% of cancers in a cancer group is said to be 90% sensitive (not 90% specific).

[saraiva]

So here's a problem:

In the original Final Fantasy game, you had to build a party of 4 "warriors of light" (characters), and there were 6 classes each character could be, independent of one another: warrior, thief, monk, black mage, white mage and red mage.

How many parties can the player build to start a new game with?

[riccvven]

not the best video, kind of confusing