Intro to Conditional Probability

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  • Опубліковано 29 вер 2024
  • What is the probability of an event A given that event B has occurred? We call this conditional probability, and it is governed by the formula that P(A|B) which reads "probability of A given B" is equal to the P(A intersect B)/P(B). We look at an example involving the probability of being an alcoholic given that one is a man.
    Conditional Probability Formula: P(A|B) = P(A and B)/P(B)
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КОМЕНТАРІ • 710

  • @DrTrefor
    @DrTrefor  4 роки тому +79

    More Conditional Probability Examples:
    Vid 1: ua-cam.com/video/OYT0AcuLXu8/v-deo.html&ab_channel=Dr.TreforBazett
    Vid 2: ua-cam.com/video/nz-ADHZrYxk/v-deo.html&ab_channel=Dr.TreforBazett

    • @superslimey7780
      @superslimey7780 4 роки тому +1

      nice

    • @ParadymShiftVegan
      @ParadymShiftVegan 3 роки тому +1

      3:58 LGBTQ+ just got triggered 😅

    • @metro.mayor_
      @metro.mayor_ 3 роки тому

      Both qualify for where's my Subway sandwich to in ⁰0⁰⁰000⁰00p ppppp0pppppp0ppppppppppp 0⁰⁰0⁰0⁰pp⁰ppppppp ppppp0pppppp0ppppppppppp p⁰00p⁰00⁰⁰⁰⁰0⁰⁰⁰⁰⁰pppppppp ppppp0pppppp0ppppppppppp ⁰⁰00000⁰⁰0⁰⁰⁰000⁰⁰⁰000⁰⁰009990 00

    • @phellisbonah8012
      @phellisbonah8012 2 роки тому

      Ok

    • @ramyhuber8392
      @ramyhuber8392 2 роки тому

      Wow what a fun video! Reminds me of "if then" statements applied to likelihood of real life situations occurring.

  • @arcadian3090
    @arcadian3090 3 роки тому +1493

    I entered wanting to learn math, and I exited with knowing I have a good probable chance of being an alcoholic.

  • @jiovek
    @jiovek 3 роки тому +24

    this man really summed up what an hour's math lesson couldn't in less than 10 mins
    legend

  • @L2.Lagrange
    @L2.Lagrange 2 роки тому +6

    Really awesome video. Currently taking stats for electrical engineering and I really liked this conditional probability description

  • @hecz250
    @hecz250 6 років тому +6

    I think what makes these problems tricky is mistaking the statements "probability of A and B both occurring" and "probability that A will happen given B". It's important to understand that these are not the same, in this case that they are not both 2.25% probability.
    Thanks for the helpful video!

  • @nickputkaradze1181
    @nickputkaradze1181 3 роки тому +3

    This really helped me to finally understand why does that formula work. Thanks!

  • @NathanQueija
    @NathanQueija 2 роки тому +1

    Oh gosh, I finally understood the intuition behind this formula. Thanks a lot!

  • @kenho4470
    @kenho4470 10 місяців тому +1

    Amazing video. 10/10 love the enthusiasm AND ACTUALLY HELPED ME UNDERSTAND THIS FORMULA BRUH. I owe u a great debt of gratitufe

  • @stacigrimes9920
    @stacigrimes9920 Рік тому

    Thank you for breaking it down to a level that could actually be understood.

  • @heyarnold3733
    @heyarnold3733 2 роки тому +3

    wow, you explained tyhis so well! better than my professor. thank you so much!!

  • @rndmguy001
    @rndmguy001 3 роки тому

    I have a final tonight for an expert systems class. My professor explained this with the P(A|B) relating to P(B|A) which if you're like me and can't remember what that is is useless. Thanks for clearing this up because I have to remember this for Baye's Thm. God help me.

  • @sumukhsonkar3136
    @sumukhsonkar3136 3 роки тому +2

    Thankyou so much ,
    Very well explained..., This topic is one of the topics in the syllabus of of competitive exams m going to appear this month (in India),
    I checked some your videos and those are really helpful... Thanks again 🙏🏻

  • @gatizgangawat2068
    @gatizgangawat2068 2 роки тому +1

    I paused for a minute and realised m actually getting it🤪..thx.🌈

  • @akosuafrimpong4465
    @akosuafrimpong4465 3 роки тому

    This all finally makes sense. You're God-sent; thanks a bunch!

  • @anishkhadgi6822
    @anishkhadgi6822 3 роки тому

    amazing, the example helped in understanding the concept of conditional probability

    • @DrTrefor
      @DrTrefor  3 роки тому

      Glad it was helpful!

  • @yavdhesh
    @yavdhesh 4 роки тому

    नमस्ते, आप बहुत अच्छे से समझाते है ।

  • @souraple101
    @souraple101 5 років тому +1

    So glad I found your video. This concept actually makes sense finally. Thank you! :)

  • @abdussamad9399
    @abdussamad9399 3 роки тому +1

    Wow, just amazing! You saved my day!

  • @ucheobi7430
    @ucheobi7430 5 років тому

    Very very well explained, much better explained than at uni

  • @diegocasab2136
    @diegocasab2136 2 роки тому

    Thank you, figured it out fast with your video

  • @xadam9979
    @xadam9979 5 років тому +3

    I have a math test tmr and I’m learning the unit right now...I’m so fucked

  • @Michael-rc5ks
    @Michael-rc5ks 3 роки тому

    What would be the difference between:
    1. The probability of a red ball
    2. The probability of a ball given that it is red.

  • @dusicamilosavljevic6718
    @dusicamilosavljevic6718 4 роки тому

    Now I really understood it after so many failed attempts. Thank you!

  • @dflash1019
    @dflash1019 4 роки тому

    this is amazing you answer all the questions and made everything clear best ever i'm definitely watching the next video for more examples that's liked and subscribed.

  • @DanishAhmed-vz6sh
    @DanishAhmed-vz6sh 3 роки тому +1

    Thank you Dr. Trefor!

  • @andrexeme_swag
    @andrexeme_swag 3 роки тому

    Got to love the way you explain. Great video!

  • @michaelbauers8800
    @michaelbauers8800 5 років тому +1

    I enjoyed a cocktail while watching this video ;)

    • @michaelbauers8800
      @michaelbauers8800 5 років тому

      I got a minor in math in college, and I applaud your clear presentation of this stuff. I am working my way through an entire book on the Monty Hall problem, using a lot of Bayes, so watching all your related videos to get another explanation of the math ( I simply don't recall covering this in my prob. class.)

  • @orbambassador5158
    @orbambassador5158 4 роки тому

    thank you man you saved my ass the day before the test

  • @xarran
    @xarran 2 роки тому

    Now what is the conditional probability density of matrix A, given matrix B has occurred when A = B + ϵ∼N(0,σ2)?

  • @kashifmoon2000
    @kashifmoon2000 3 роки тому +1

    outstanding

  • @nielsnaser4793
    @nielsnaser4793 Рік тому

    The interesting way is, how de F do you get the intersect becaus it can be calculated in two ways. Evrey where i search i see two ways of getting the intersect

  • @yasminamin1893
    @yasminamin1893 5 років тому

    it is sold ...thank you

  • @joshuang7477
    @joshuang7477 4 роки тому

    Amazing, you explain it so well. Thank you so much sir!

  • @gbenromoyinoluwa1950
    @gbenromoyinoluwa1950 11 місяців тому +2

    The probabiity of being a man or woman is not 50% anymore 😭😭

  • @nothing82477
    @nothing82477 6 років тому

    Brilliant video. Well explained!

  • @jevlon8736
    @jevlon8736 3 роки тому

    Using conditional theorem can I manipulate it so that I can use it to get P(B)= (P(A) and p(B))/P(b|a)

  • @salwah1707
    @salwah1707 6 років тому

    Very well explained. Thank you for this!

  • @mahirpokar1528
    @mahirpokar1528 6 років тому

    Best explanation ever!!!!

  • @ambassador-of-misogyny
    @ambassador-of-misogyny 2 роки тому

    5:44 Based denominator

  • @WesternJiveStudio
    @WesternJiveStudio 6 років тому

    Great explanation! Thank you!

  • @stellaunya5192
    @stellaunya5192 5 років тому

    Thank you so much.

  • @Lee-we2xu
    @Lee-we2xu 2 роки тому

    Very nicely explained ! :)

  • @donjour69
    @donjour69 2 роки тому

    Hahaha 🤣🤣🤣🤣🤣 Bad Education vibes
    You even sound like Jack Whitehall doing an American accent

  • @Ben-bg2lp
    @Ben-bg2lp 4 роки тому

    Beautiful

  • @ants070
    @ants070 4 роки тому

    Thanks pew

  • @MGPL_
    @MGPL_ 3 роки тому

    I'd give this guy... oh, I dunno... a 4.5% probability of being an alcoholic

  • @osamakhan2832
    @osamakhan2832 4 роки тому

    How did you get 0.5?

  • @towhidskynet
    @towhidskynet 5 років тому

    Lucid explanation.

  • @jesusaranda3726
    @jesusaranda3726 6 років тому +1151

    Took me nine minutes to understand what I couldn't get in a fifty-minute lecture. Thank you.

    • @alejandratrujillo1312
      @alejandratrujillo1312 5 років тому +2

      Same here! You saved my life!

    • @Tintin-dm4ym
      @Tintin-dm4ym 5 років тому +21

      Jesus Aranda it’s a 6 min video XD

    • @adityashinde1079
      @adityashinde1079 5 років тому +14

      @@Tintin-dm4ym his maths is weak 😂

    • @alisheikh3585
      @alisheikh3585 5 років тому +9

      @@adityashinde1079 lol, he probably spent a little more time on a particular concept!

    • @gytisdramblewolfskis8521
      @gytisdramblewolfskis8521 5 років тому +11

      This concept is so simple as well as complicated if explained badly. The visual representation means so much

  • @simplematters4893
    @simplematters4893 4 роки тому +327

    Who’s here during covid19 online learning

    • @Abdussalam-ml3so
      @Abdussalam-ml3so 4 роки тому +4

      @@DrTrefor lol

    • @143woww
      @143woww 4 роки тому +13

      I am doing statistic online and it is driving me nuts 😂

    • @________4423
      @________4423 4 роки тому +2

      @@DrTrefor The probability of that occurring is beyond certain.

    • @adeliadrawstuff
      @adeliadrawstuff 4 роки тому +2

      ayan aden this topic is the most stressful one for me and it’s my second time taking the class 😣

    • @DrTrefor
      @DrTrefor  4 роки тому +20

      Good luck everyone with your online courses:)

  • @redwillowofdreams8931
    @redwillowofdreams8931 6 років тому +589

    Stop reading the comments and get on with your homework.

    • @nitamac1312
      @nitamac1312 6 років тому +71

      stop writing comments and get on with your homework

    • @bakonator4845
      @bakonator4845 6 років тому +25

      Redwillow of Wattpad, it’s too late my pet goldfish already ate my homework. I’m just studying for a test

    • @steveworldwar2
      @steveworldwar2 6 років тому +3

      Fuck you

    • @jackbrookes21
      @jackbrookes21 6 років тому +11

      i feel attacked

    • @aishaelmubarak8689
      @aishaelmubarak8689 5 років тому

      @@bakonator4845 fuck u

  • @rileyregan2900
    @rileyregan2900 3 роки тому +145

    You explained this WAAYYYYY better than my professor and khan academy COMBINED. Not sure why they made it sound so damn complicated

    • @louiselin3928
      @louiselin3928 3 роки тому +4

      Yeah, it is the only video (I saw) that gives the meaning behind the formula. And this is exactly what I want.

    • @suyashpal803
      @suyashpal803 2 роки тому +2

      People understand words better than formula but at the end of the day a formula is what you need to solve maths and no.
      Please note : I came here looking for formula..I guess I should check khan academy..lol

    • @emperor8716
      @emperor8716 9 місяців тому

      @@suyashpal803 the formula is literally right there at 1:15. he even shows an example of it.

  • @felixhall6429
    @felixhall6429 5 років тому +311

    Thank you!! I now feel ready for my exam tomorrow 😅 (anyone else in the same boat?)

  • @ramtinshahali9944
    @ramtinshahali9944 2 роки тому +86

    Took my professor 2hr to explain this topic and NO ONE could not understand a word of what he said while it took you like 5min to teach this and now I can solve all the problems he gave us. You're a lifesaver so thank you. Universities should understand having a PHD in math does not make you a good professor, being able to teach is completely different from having the knowledge. But you Dr.Trefor, have both the knowledge and you know how to teach math.

    • @alang.2054
      @alang.2054 8 місяців тому +1

      Maybe you was just familiar with the topic thanks to your professor and video just served as a resource to ground your understanding?

    • @acanadianfry2539
      @acanadianfry2539 5 місяців тому +2

      @@alang.2054 nah, most profs arent teachers w/experience. a bunch of it is just funding for researchers. Theyre just given a syllabus.

    • @TheRedCubeYT
      @TheRedCubeYT 5 місяців тому

      Ur learning secondary school level maths at uni??

  • @reasetilo
    @reasetilo 2 роки тому +10

    time to save the semester ...

  • @justinlu9399
    @justinlu9399 6 років тому +34

    THANK YOU SOMEONE FINALLY EXPLAINED THE FORMULA WELL ENOUGH FOR AN IDIOT LIKE ME

    • @Margauxhoney
      @Margauxhoney 6 років тому

      and another idiot like me too, haha

  • @spicyboi1825
    @spicyboi1825 3 роки тому +36

    As someone who is hard of hearing, I really appreciate the effort put into the subtitles, thank you.

  • @supersql8406
    @supersql8406 4 роки тому +29

    I like how Tefor is really a smart guy, but he does his best to explain it in layman's term... sometimes the vocab in itself can be confusing for those who just starting...

  • @thegrinch2613
    @thegrinch2613 4 роки тому +37

    I have a test tomorrow and I could never do conditional probability, but now you've made it seem so easy, so thank you!

    • @paulolelewe2330
      @paulolelewe2330 2 роки тому

      Teachers at Cerritos College teach similar topics but some of them possibly have their bachelor's degree. Most of them are probably from Long beach or any city using the beaches/towns and cheaper places to live.

    • @Nigerian_KO
      @Nigerian_KO 10 місяців тому

      Same here 😢

  • @jaspermartin7444
    @jaspermartin7444 5 років тому +18

    whoa, you explain this better AND in a shorter amount of time, then the MIT guy. more videos please!

    • @SciHeartJourney
      @SciHeartJourney 3 роки тому +1

      The MIT guy is too busy trying to impress you with his brilliance. He treats us like he doesn't have time to school you. 🙄

  • @MrLiamcfc
    @MrLiamcfc 6 років тому +47

    Jack Whitehall you are a lifesaver bro

  • @bodick327
    @bodick327 5 років тому +174

    if you are a man, and a russian, your probability of being an alcoholic is 100%

    • @piyushuniyal6129
      @piyushuniyal6129 5 років тому

      бодяныч what if you are a woman?

    • @bodick327
      @bodick327 5 років тому +11

      Piyush Uniyal, if you are women in Russia, probability of being single and have 10 cats is 20%, other 80% is for being married and get beaten by your husband👍

    • @zac2981
      @zac2981 5 років тому +1

      @@bodick327 really?
      why so serious?

    • @Thehamstersgiude2u
      @Thehamstersgiude2u 5 років тому +1

      бодяныч what about the probability of being a Russian man and committing suicide?

    • @paritoshagarwal8840
      @paritoshagarwal8840 4 роки тому +3

      probability of becoming president in russia?

  • @Mel-nx6dp
    @Mel-nx6dp 3 роки тому +5

    going into my final exam in a couple hours and I finally understood this concept omfg

  • @ericarocha7659
    @ericarocha7659 12 днів тому +1

    Thank you for explaining this. I have a quiz at 9 am tomorrow, and my professor spent 2 lectures that are 2 hours long to explain what you explained in 5 minutes thank you so much; I need to pass stats so bad.

  • @lowrenz4277
    @lowrenz4277 4 роки тому +1

    Can someone help me with this example? If you start with the assumption that the probability of being an alcoholic is: p(A(male)) + p(A(notMale)) / p(male) + p(notMale) and then you assume that you are a male, so the whole not male goes away: p(A(male)) / p(male) we have the formula in the video.... but when we then consider what p(A(male)) means: 2.25% of all male... so we divide again by the number of males.. isn't that kind of self referential in this example?

  • @mrbobm00
    @mrbobm00 3 роки тому +5

    Given that we always divide by a number

    • @DrTrefor
      @DrTrefor  3 роки тому +6

      Absolutely. We now know more than we used to, which makes our confidence more likely.

  • @HabibiGa1z
    @HabibiGa1z 3 роки тому +1

    If the probabilty of being an alcoholic as male is 2.25%, then that answers the question? If a doctor walks in and sees a male patient, she knows the chance of him being an alcoholic is 2.25%. What am i missing here? Or is the question: "What is the probability of a doctor seeing a patient who IS a male AND an alcoholic"?

  • @astrixcuber7986
    @astrixcuber7986 11 місяців тому +3

    50% male 50% female is W

  • @MarzanaTamanna_
    @MarzanaTamanna_ 2 роки тому +1

    I had come here to learn probability but I can not move my eyes from you where i should focous on your lecture 🙆‍♀️❤️
    Btw your lecture is very helpful though 🤷‍♀️

  • @VilladsClaes
    @VilladsClaes Рік тому +1

    What is the best tool to graph Venn-diagrams based on data? (So The Smart-Art-feature of Excel does not count)

  • @GoAndPraySalah
    @GoAndPraySalah 4 місяці тому +1

    Probability of being either male or female = 50%
    LGTV people watching this : 💀

  • @christyblazee4770
    @christyblazee4770 3 роки тому +3

    Hello sir! Thank you for this i just wanna ask where did you get 0.5?

    • @SuperBiggates
      @SuperBiggates 2 роки тому +1

      same

    • @빌디-z6g
      @빌디-z6g Рік тому

      Half of the population is male, half is female. So P(male) = 0.5

  • @mrbagginz5963
    @mrbagginz5963 5 місяців тому +1

    My god thank you so much im a 6th grader who enjoys math and learning about the why and you gave so many reasons this made sense! I’ll definitely watch you more and thank you 😂

  • @keto0592
    @keto0592 6 років тому +3

    where did you get .5? was this an assumed given?

  • @MagnusTheGreat
    @MagnusTheGreat 6 років тому +14

    Why is this so hard

    • @SciHeartJourney
      @SciHeartJourney 3 роки тому

      I can give you a long text that doesn't even show a Venn Diagram; that's why. This video made it easy to see and understand.

    • @tuvelout
      @tuvelout 3 роки тому

      for a student doing revisions, it is not that great, since it has lots of explanation. For a beginnener I would say cause first, it is boring AF :v, secondly because it requires a hot reasoning and capability to remember, think about it, and to apply what you just learned, ANd then never use again. Let me say, that is messed up! 🔥

  • @udonwarrior9983
    @udonwarrior9983 6 років тому +32

    Best explanation!

    • @TH-cq8jy
      @TH-cq8jy 3 роки тому

      Who do you support in La Liga?

  • @richardfeynman7332
    @richardfeynman7332 4 роки тому +3

    Man!!!! you just need a lot of subscribers....

  • @27Gebordi
    @27Gebordi 7 місяців тому +1

    Please how did you get the 0.5???....
    As the probability of the man???....

  • @ALele14Baller
    @ALele14Baller 5 років тому +8

    BLESS YOU!!! I can't ever understand my professor who's lectures are an hour and 40 minutes long, and I just learned it all in 6 minutes!!!

  • @kimp.dr.n2652
    @kimp.dr.n2652 2 роки тому +1

    I m failing these word problem every freaking time! Why with the word riddles?

  • @BoxOfCurryos
    @BoxOfCurryos Рік тому +2

    Stats makes me want to become an alcoholic.

  • @arunkumarpapanna7962
    @arunkumarpapanna7962 4 роки тому +1

    How's it about 2.5% for adult females? Can you please explain?

  • @Vlfkfnejisjejrjtjrie
    @Vlfkfnejisjejrjtjrie 6 років тому +6

    I just finished off a case of beer while watching this. What's my chances with cirrhosis of the liver? ☠

  • @OmnipotentZORG
    @OmnipotentZORG 3 роки тому +2

    Oh my gosh thank you, I was overthinking it so much. I have an applied statistics midterm tomorrow!

  • @sayakroy691
    @sayakroy691 3 роки тому +1

    i can assure you there is really high probability of me liking this video

  • @mohamedeljahmi2454
    @mohamedeljahmi2454 2 роки тому +1

    Why the probability of a woman being an alcoholic is at %2.5? How did you get that number?

    • @DrTrefor
      @DrTrefor  2 роки тому +1

      This was not an assumption, it was the result of plugging the numbers into the conditional probability formula for P(alcoholic | women)

  • @eventhorizon492
    @eventhorizon492 Рік тому +2

    wow, hours of suffering undone in a six minute video. Lifesaver dude, thank you

  • @muhammadwaseem_
    @muhammadwaseem_ Рік тому +1

    People like you should teach math is schools, so that kids would love maths

  • @kamalgopalsingh244
    @kamalgopalsingh244 4 роки тому +1

    Pls tell how for adult female it is going to be 2.5%, please

  • @Bondhio
    @Bondhio Рік тому +1

    One shot, two shot, three shot, floor. Fuck this math homework.

  • @cb27743
    @cb27743 2 роки тому +1

    Paid tuition instruction: "bla bla bla i hate my job, math it yourself"....Guy on UA-cam who is passionate "oh buckle up, i have some awesome examples for you" Thanks again Dr. Bazett!

  • @nasirbudhah3063
    @nasirbudhah3063 4 роки тому +1

    It is easier to understand it if written as P(A and B) = P(A|B)P(B)

  • @alexisjainet9710
    @alexisjainet9710 4 роки тому +1

    Can someone help me with this problem-
    P(a)=0.65, p(b)=0.40, p(a and b)=0.28. Are a and b mutually exclusive?
    Find a or b

  • @ShallowPorcupine
    @ShallowPorcupine 5 місяців тому +2

    Conddditional probability

  • @nathanlu9959
    @nathanlu9959 2 роки тому +1

    Its the little things like explaining notation that really helps... like our professors just expects us to know what theyre talking about. if i did know, I wouldn't be in your class!

  • @JoeG2324
    @JoeG2324 5 років тому +1

    your assuming there are only 2 genders with that 50%

  • @rupeshk4803
    @rupeshk4803 3 роки тому +1

    @0:12..how is ur hand cut off 🙄

  • @interfaze9930
    @interfaze9930 2 роки тому +3

    I'm studying general engineering and I did not have a lot of statistics in my curriculum. The bit that I had I have already forgotten again. Now I need a LOT of statistics for my master thesis. You are saving me so much time! Much appreciated!

  • @A_Data
    @A_Data 4 роки тому

    Hey, I have a question. What is the probability of a certain country winning 1 gold medal in the tokyo olympics. My only information gathered is the number of participating athletes in each country. Please help.

  • @vanilla7045
    @vanilla7045 Рік тому +1

    thank you soo much...i literally love u😍🥰