Conditional Probabilities, Clearly Explained!!!

[@statquest]

NOTE: Conditional probabilities can be written two ways: a "long" version and a "short" version. In this video I use the long version (because it's easier for me to read)... P(A and B | B) = P(A and B)/P(B) ...however, the short version is commonly used... P(A | B) = P(A and B)/P(B) Both mean the same thing, in other words: P(A and B | B) = P(A | B). The short version implies the "and B" part. Support StatQuest by buying my book The StatQuest Illustrated Guide to Machine Learning or a Study Guide or Merch!!! statquest.org/statquest-store/

[@exploringdiversity572]

Your version is much easier for non-statisticians like me :)

[@statquest]

@@exploringdiversity572 bam!

[@chandrashekar316]

omg this cleared up so much confusion i had from reading my text book where they were using the shorthand

[@pomegranate8593]

I love how I need a video that seems designed for 7 year olds to understand my uni course. Great vid thanks

[@statquest]

Glad it was helpful!

[@BulbasaurLeaves]

I like the style. It's fun and nostalgic

[@TheRedCubeYT]

this is secondary school level maths

[@nsuinteger-au]

bam!

[@asrao3788]

In India due to competition for engineering entrance exam teacher majorly focus on question types rather than concept in depth. Im glad there is a place where people learn for fun not just for competition, also appreiciate teachers like you who can turn subjects into magic. Keep up the good work! From now on I'm permanent on this channel. You are the best!

[@statquest]

Thank you very much!

[@shinej11]

I always thought I was incapable of learning math, but it had always intrigued me. I just discovered what was missing; a good teacher. Thank you very much.

[@statquest]

bam!

[@PastryDonut]

I'm in the same boat as you man, love this channel

[@mikejohns1347]

I "stumbled" upon the contingency table method many years ago when trying teach myself the basics of probability. This approach is really the only approach for developing a solid understanding of conditional probability, as well as joint and marginal probability. I've never seen anyone present it this way and I'm so glad to see it here! Just more evidence that Josh Starmer is an absolute master instructor.

[@statquest]

BAM! Thank you very much! :)

[@endahfajarwati8336]

you know, me too.

[@Ash-bc8vw]

Hey this table reminds me of confusion matrix from a ML classification problem

[@turtle3341]

this is how i wish people taught stuff, i really hope these ways of learning statistics get the recognition they deserve! please keep it up !!!!

[@statquest]

Thank you!

[@azinkhodadadi7912]

I should of paid you instead of my useless lecturer at university! This is so much more useful thank you!

[@statquest]

Glad I could help!

[@drpkmath12345]

Very nice video for sure. Conditional prob is one of the topics students feel the most difficulty when they start studying for stat! Great job!

[@statquest]

Thank you! :)

[@siennadae-knight5598]

Just about started crying when the cartoon-y jingle and graphics started and felt a weight lift off my shoulders when you introduced the contigency table. I have 0 background in prob and stats, always hated the subject, and was terrified it would be impossible for me to learn. None of the symbols made sense to me. The concepts gave me a headache. And I wouldn't even know where to begin asking questions considering no matter how much I seemed to "understand" what my professor was saying in class, the moment I saw a homework question, complete blank. I thought I was doomed to just memorizing formulas that made no sense to me, which isn't a great thing to say as an engineering student. Thank you. I've been saved by your channel.

[@statquest]

Happy to help! :)

[@usethisforproductivity-tg7xq]

erm what the sigma

[@rejithmadhavan5735]

Logical explanation, precision and genuineness - your way of teaching exemplifies these essential qualities. Thanks so much Josh for these great lessons. Invaluable effort!

[@statquest]

Wow, thank you!

[@baqirhusain5652]

You are a GOD of simple explanations

[@statquest]

Thanks!

[@jacob.9664]

Soda and Candy > Mechanical engineering degree. Thank you it was very helpful!

[@statquest]

BAM! :)

[@IarukaSkYouk]

I FUCKING HATE PROBABILITIES SO MUCH I ACTUALYL GAVE UP 3 TIMES LEARNING THE COURSE (THE COURSE IS HIGH QUALITY IM JUST VERY STUPID) IM SO SO SO GLAD IM STARTING TO GET IT FROM YOUR VIDEOS JOSH. YOU'RE DEFINITELY THE #1 GUY ON KZbin.

[@statquest]

thanks! :)

[@Florithepenguin]

Struggled with this topic literally for years! You solved my problem within just 10 min.! 🎉

[@statquest]

Bam! :)

[@tyt03538]

This is the best video explaining conditional probability. Hands down.

[@statquest]

Thanks!

[@AndrywMarques]

Great video! I never saw the "long version" to write conditional probabilities before but it's better to understand. Very intuitive!

[@statquest]

Yes, I like it more, too.

[@minettelamprecht90]

I am forever in my uni lecturer's debt for being too lazy to explain and instead give us the link to your index!! I need to learn stats as part of my Data Science Programming course, and you have been VERY helpful

[@statquest]

BAM! Good luck with the course!

[@Regular.Biceps]

Exceptional explanation... I'm Completely in love with your teaching style

[@statquest]

Thank you!

[@HardikBhakhar]

Never thought that to understand conditional probabilities is this easy … thanks prof 🎯

[@statquest]

bam! :)

[@talentlancer1358]

Thank you so much! This is the best video on conditional probability on internet.

[@statquest]

Thank you!

[@Oliver-cn5xx]

Hi Josh, I am a long time fan of your channel and all of the shameless self-promotion has guilted me into buying one of your study guides (LDA). They seem great, a nice supplement to your videos. Though I think you would benefit greatly from stripping down the ordering process, I mean for online purchases almost noone asks for complete addresses, phone numbers and names anymore. I fought very hard with myself to finish it and parting with that information, and I succeeded simply because of being so grateful for the videos you provide. You'd probably sell a lot more of these if you just ask for an email. Like most. Cheers

[@statquest]

Thanks for the advice! I'll see what I can do to simplify the ordering process.

[@jacktaylor1516]

This is one of the best explanations of absolutely anything I've ever seen and heard. Well done. Subscribed.

[@statquest]

Awesome, thank you!

[@phuctran4679]

Thank you Josh & the team. I'm so grateful I've found your channel. You make me truly love statistics!

[@statquest]

Glad you enjoy it!

[@Nakameguro97]

Thank you SO MUCH for clarifying that AB = A and B, when A and B are events. I get confused because XY is literally multiplication when X and Y are random variables. It can be doubly confusing because both events and random variables (even though they are different types) can be passed into P(), the probability function. Function overloading is a thing in computer programming, but I’m shocked to see it in math. Also, the implied A and B in P(A | B) is a lifesaver, many times over. BTW, understanding the tables in this video is pivotal in grasping marginal distributions, Baye’s Theorem, and joint probability distributions - it feels like I’m getting the other three concepts for free!

[@statquest]

Triple bam!!! :)

[@dizetoot]

THANK YOU! I've really been struggling to get an intuitive understanding of conditional probability and this has helped so much!

[@statquest]

Glad it helped!

[@leandroimail]

I love these classes. They are so easy to understand. Thks you for sharing with us!

[@statquest]

Thank you very much! :)

[@onurkrmz9206]

Today I discovered your channel and it is truly a gem. As a EEE student who tries to make sense of subject of probability and neural network stuff, I believe I will benefit a lot from your work and be thankful for rest of my life. Especially statistics is challenging as things get messy a lot and scary/unintuitive equations with confusing notations start to appear. I did not look at all of your videos yet, but I hope that you did statistics less scary for those like me. My best regards

[@statquest]

Awesome! Here's a page that lists all of my videos (and playlists etc): statquest.org/video-index/

[@vavy5652]

You are literally saving me from my statistics exam! Thank you so much, your explanations are brilliant and you are really making me focus with your simple and funny ways. Thank you again!

[@statquest]

Good luck! :)

[@between_the_lines6173]

You're the statistics buddha! The analogies and the calming voice!

[@statquest]

Thanks!

[@buihung3704]

A 6 years old can understand this. That's genius

[@statquest]

Thanks!

[@arpitkakkar2780]

Awesome. I always come here to get my doubts clear. Love the way you teach. Lots of BAM!!!

[@statquest]

Thanks!

[@colinirvine757]

Great job Josh!!!!! This is such a clear and precisely laid out video perfect for my students.

[@statquest]

bam!

[@tamminh480]

cant express how grateful i am to stumble across your channel!!!! I thought I was dumb but not anymore haha

[@statquest]

bam! :)

[@ShashwatAgarwal007]

Happy Guru Purnima Sir, So blessed that this channel exists. ❤️🙏

[@statquest]

Thank you! And thank you for supporting StatQuest! BAM! :)

[@tomr03status99]

❤️❤️

[@dhendroid2373]

This is how every tutorial should be!

[@statquest]

Thanks!

[@ivlivs.c3666]

Incredibly well-explained. Thank you!

[@statquest]

Thank you! :)

[@faiazrummankhan5589]

This channel is the bible of " Making 'Understanding Statistics' Easy !"

[@statquest]

bam! :)

[@uvofsam]

Bam!! , what a bam person to explain everything about statistics so bamly!!

[@statquest]

Thanks!

[@NoahElRhandour]

Bamks!

[@jacktrimboli]

I get a dopamine rush every time this man says bam

[@statquest]

bam!

[@jerryquid4057]

You're incredible. You make everything seem so easy

[@statquest]

Wow, thank you!

[@AbcdAbcd-ol5hn]

😭😭😭😭thanks a lot😭😭😭god bless you, u are doing a noble job, may you get all the riches, love and happiness in the world

[@statquest]

Thank you very much! :)

[@ramprakash7872]

Conditional probability : Decoded. BAM !!! Tbh Some of your videos ( Very few actually. For example p-value 😁) were not very clear to me ( Well that's just me ! ) in the first instance but I digested through them somehow. But with little study & focus or just give a break for a while, the 2nd or 3rd look at your video makes the concept super clear to me and I don't need to look elsewhere. Thanks for making such videos and making statistics/probability easier.

[@statquest]

I'm glad you are able to understand the concepts.

[@prachisharma457]

Omgg I finally understood this Bam!!

[@statquest]

bam! :)

[@BARAKABLESSING]

This helped understand c prob. I am taking a mandatory into to stat class with no math experience and passion. Thanks

[@statquest]

Good luck!

[@amribrahim7850]

Awesome explanation. Thanks to you and Triple Bam members

[@statquest]

Glad you liked it! BAM! :)

[@shamsulazhar]

Finally, I understand this. BAM!!!!

[@statquest]

Bam!

[@tsigeasteraye4485]

This is amazing way of explanation!

[@statquest]

Thanks!

[@josevaldes7493]

amazing googleplex BAM! Man you did it again. BRAVO

[@statquest]

Wow, thanks!

[@sanjeevsingh-zz2hg]

Your way of teaching ! Bam!

[@statquest]

Thanks!

[@ahmadatta66]

"I hate using abbreviations" And I love you for that

[@statquest]

bam!

[@anthonyrinna1305]

First, I'll admit I had "Do you love orange soda?" from Keenan and Kel in the back of my mind. That said, this video has been immensely helpful, thank you!

[@statquest]

:)

[@kayhankashi9970]

SUPERB explanation... BAAAM !!!!!

[@statquest]

Thanks!

[@yujan9103]

Well explained. Bit long but makes the concept clear as possible. A big THANK YOU Josh.

[@statquest]

Thanks!

[@gabrielasantana3809]

And BAM! I subscribed….such a clear explanation

[@statquest]

Awesome, thank you!

[@sillyfarmerbilly8872]

"statsquatch" I love it 😂 Also I guess I never put together that you could use the probabilities to calculate conditional probabilies, super helpful

[@statquest]

BAM! :)

[@swarnachoppella388]

Thank you! Great content always🤩

[@statquest]

My pleasure!

[@dyles1832]

The people demand a Montecarlo Simulations StatQuest!!!

[@justinwhite2725]

That would be nice.

[@statquest]

I'll keep that in mind. We may get to something like it when I cover bayesian statistics.

[@tomr03status99]

That could be nice

[@LightFlameGamerOP]

BAM! You just got a new subscriber 😂

[@statquest]

Thank you!

[@simonroques8579]

Excellent video..again ! So good to be hit by the triple bam !!! 😁

[@statquest]

Hooray! :)

[@pratyushkashyap849]

Incredible lecture!! Bamm😀

[@statquest]

Thank you!

[@avrilduck8326]

After 4:40, I cried "that's enough" because it was relentless!!

[@statquest]

bam

[@rishikeshpillay]

Thanks for this explanation.....It really help me to grasp this topic....

[@statquest]

Bam!

[@MuspiMeroll]

i love you this actually helped so much

[@statquest]

Thanks!

[@LukaszWiklendt]

It's interesting notation that you keep the superfluous condition on the left side of the pipe. I.e. using p(c=0 and s=1 | s=1) instead of p(c=0 | s=1). Do you find students understand it better this way?

[@statquest]

Yes. To me it is much clearer.

[@vinodliyanage4128]

Best explanation ever. Thank you! ❤️

[@statquest]

Thank you! :)

[@kensarmoreto1863]

although that i calculate conditional probability during college, i cannot get the concept of it leaving a gap in my stat knowledge... i stumbled in your video and i have a basic understanding about it. im just need a more examples regarding conditional probability to fully master this concept... Thanks Josh for your videos and hoping for more topics about stats and data analysis.

[@statquest]

I'm glad my video was helpful! :)

[@BrittanyFunke]

This was amazing and fun. Thank you!

[@statquest]

Glad you enjoyed it!

[@zaf3153]

Super easy ti understand! Thanks alot

[@statquest]

Glad it helped!

[@CW-vl9zd]

Good video that cleared up a lot of my questions. Only thing I'm confused now tho is 9:20 let's say we are given all the probabilities. How do I know if a probability is p(not love c and loves s | loves s) or p(loves s | not love c and loves s)? Confused because we know both the numerator and denominator. Thanks

[@statquest]

Well, the second one, p(loves s | not love c and loves s), really doesn't make sense to calculate at all. This is because the conditional part, "not love c and loves s" is only a subset of "loves s", and thus, the conditional part does not give us any useful information about the larger "loves s" population.

[@CW-vl9zd]

@@statquest Thank you!

[@kekahazra9769]

Bam! I like the way you teach.....keep up!....Bam Bam!😅

[@statquest]

Thank you very much! BAM! :)

[@anashaat95]

Thanks a lot. Clearly explained as you stated.

[@statquest]

Thank you!

[@markobe08]

Josh is the best

[@statquest]

Thanks!

[@tomr03status99]

Yeh!

[@durgeshkshirsagar116]

Wow. Great explanation with nice song ❤️❤️

[@statquest]

Thanks a lot 😊!

[@durgeshkshirsagar116]

@@statquest welcome sir 🙏🏻

[@sudhamjayanthi]

thank you, uncle bam!

[@statquest]

My pleasure!

[@surendrabarsode8959]

Very well explained as usual!! BTW, do you have any plans for making videos on stochastic calculus topics like Brownian motion, Ito integral, martingale measures etc. If so, I am looking forward to them.

[@statquest]

I'll keep those topics in mind.

[@tomr03status99]

👍👍👍👍

[@janiceoou]

I was looking for sth like this recently, thanks for somehow read my mind XD (I guess some kinda probability?? BAM!

[@statquest]

BAM! :)

[@helgemeyer6511]

What is the probability of a video being great GIVEN that we know it is made by Josh? Pretty close to 100%, I'd say!

[@statquest]

BAM! :)

[@sigmakings7285]

That's a great one.thank you😊

[@statquest]

Glad you liked it!

[@graningfire1776]

Quadra BAMMMM ! ITS now clearly cleared in my mind

[@statquest]

It's not clear? What time point, minutes and seconds, was confusing?

[@graningfire1776]

@@statquest sorry sir , I wish to write now but due to my mistake it become not .

[@piruthuviraj]

Thank you so much...Now I cleared. 😁🥰🥰

[@statquest]

bam!

[@animelife9351]

Because of you, I knew this Concept "BAM" 😹😸

[@statquest]

bam!

[@RaceyBeats]

So bloody good!

[@statquest]

Thanks!

[@micahdesign6657]

best video ever !

[@statquest]

:)

[@yonatanaquinteror2989]

Awesome! BAM!!!

[@statquest]

:)

[@sampathkumar3405]

Josh , Please start a series for mathematics concepts for machine learning. Such as probability, linear algebra, statistics, calculus etc.. It'll great help for us.

[@statquest]

I have a bunch of statistics videos here: statquest.org/video-index/

[@lakshman587]

If we take Event A:Not loves candy Event B:Loves soda Then general formula is P(A∩B|B)=P(A∩B)/P(B) Is the above formula same as P(A|B)=P(A∩B)/P(B) (This is the formula I was taught)

[@statquest]

Yes, they are the same. The formula that you were taught is harder to read than the one I use, so I don't use it.

[@lakshman587]

@@statquest Ok thanks a lot :)

[@justinwhite2725]

Yeah. What does upside-down-U mean?

[@justinwhite2725]

I'm gonna go out on a limb and say that 8:14, the formula on the bottom is the long form of the notation you used. And he's showing in this frame how the results are the same.

[@tomr03status99]

Yes

[@SarahFeng92]

Your channel is amazing, I wish I had discovered it earlier! Would you ever consider making the slides available for sale? I would absolutely buy them.

[@statquest]

I have some of them for sale here: statquest.org/statquest-store/

[@ceseb23]

Great video, perfect explanation, marvelous song, as always :D I would love to see a video about Generalized Linear Models( other than logistic).

[@statquest]

Thanks and I'll keep that topic in mind.

[@tomr03status99]

👍👍👍

[@mostafayounes269]

thank you ❤❤

[@statquest]

:)

[@jackfrost8969]

Excellent excellent excellent

[@statquest]

Many many thanks!

[@Darkev77]

At 5:08, is it legitimate to ask "What is the probability that someone loves candy given that we know they love soda"? Without having the "and soda" condition. Or is the fact that it's "given/knowing they love soda" implies that it has to be "loves candy and soda"?

[@statquest]

Conditional probabilities can be written two ways: a "long" version and a "short" version. In this video I use the long version (because it's easier for me to read)... P(A and B | B) = P(A and B)/P(B) ...however, the short version is commonly used... P(A | B) = P(A and B)/P(B) Both mean the same thing, in other words: P(A and B | B) = P(A | B). The short version implies the "and B" part.

[@joshuaperling2985]

amazing! the best!!

[@statquest]

Thank you! :)

[@fabianarodriguez.]

I GET IT NOW THANK U SO MUCH

[@statquest]

bam! :)

[@fabriciomagalhaessena2289]

Thank you so much for this video! It saves my life hahaha

[@statquest]

Thanks!

[@EngRiadAlmadani]

BAMMM!!!! Great work Can you make video about bayesian classifier because it's depending on conditional probability

[@statquest]

I've already done that. Here's the link: kzbin.info/www/bejne/hWOvY4isbtWXeqM

[@Darkev77]

This might sound like a silly question but, shouldn’t one expect that P(A | ~A) = 0, and vice-versa? However this conditional notation doesn’t encompass that

[@statquest]

Actually, it does. What you are asking is "The probability that someone loves candy AND does not love candy given that we know that they love candy". This results in the equation p(loves candy & does not love candy) / p(loves candy) = 0 / (6/14) = 0.

[@Darkev77]

@@statquest thanks a lot prof for your clarifications!

[@qwerty11111122]

Hi Josh! I've been working with DEseq2 a lot. Is dispersion shrinkage on your TODO list for statquest? I realize it's a little more of a niche topic for bioinformatics than broadly applicable tho

[@statquest]

I'll keep it in mind.

[@shahf13]

Great job josh you are my favorite teacher !! , can you think about making a video about Multicollinearity? bam

[@statquest]

I'll keep that in mind.

[@RajSARAF495]

Beautiful ❤

[@statquest]

Thank you! :)

[@sleepydev4700]

Hundred Bam!! Great explanation as always Could you put the playlist link in the description, it will help us a lot, thanks.

[@statquest]

Which playlist are you asking about?