Expected Value and Variance of Discrete Random Variables

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  • Опубліковано 22 гру 2024

КОМЕНТАРІ • 499

  • @screwgoogleaccounts7111
    @screwgoogleaccounts7111 9 років тому +283

    You took 8 minutes to do what my Professor has done in 17 pages of nonsense notes. I would be failing without this haha

  • @Hind-t9j
    @Hind-t9j 9 місяців тому +25

    first video that actually explains the concepts instead of just applying the formulas, thank you so much

    • @jbstatistics
      @jbstatistics  9 місяців тому

      That's what I do here :) I'm glad to be of help!

  • @parthsarthy3611
    @parthsarthy3611 9 років тому +431

    I wish my professor in university could teach students like jb does.Understood it in 5 mins.thank you

    • @SilentRyd
      @SilentRyd 4 роки тому +11

      Most professors spend lecture on theoretical side of math and proofs of theorems. They only spend a minute or two on its applications and how to use it. JB focuses on that aspect which makes him great teacher for a lot of us including myself.

    • @TG-wg4tw
      @TG-wg4tw 3 роки тому +2

      not only the prof but alot of book is confusing as he11 too. I'm currently reading the Information Theory book by Cover-Thomas and let me tell you, these E(x) just fly out from no where and a bunch of "information content" "surprise",... etc and basically means the same thing or completely different things but have the same denotation.

    • @TG-wg4tw
      @TG-wg4tw 3 роки тому +9

      @@SilentRyd wtf learning those theorems and proofs for when you can't wrap your head around the idea ? It's like when you're nearly starve to death and some one comes in, instead of showing you how to hunt they teach you about the mammal evolution.

    • @jcn268
      @jcn268 3 роки тому +1

      im learning this in college ,yall just learning this in uni?

    • @mickeychan2007
      @mickeychan2007 2 роки тому +1

      @@jcn268 I learnt this in 7th grade, just came here cuz it’s a great refresher

  • @jbstatistics
    @jbstatistics  11 років тому +44

    Thanks for the compliment! I've got lots of good stuff on this channel, and I hope you find it helpful.

  • @kokokiki
    @kokokiki 2 роки тому +33

    I've watched so many videos on expected values and variance and this was the first one I was able to really truly understand. Thank you so much for being so thorough!

  • @kaljamaha16
    @kaljamaha16 9 місяців тому +5

    I am so glad that I found this channel. I have been struggling with my university's probability and statistic course

  • @amylabelle6239
    @amylabelle6239 9 років тому +49

    All of these videos are saving my life, you are amazing at what you do JB.

  • @ojussinghal2501
    @ojussinghal2501 3 роки тому +4

    The clarity with which you explain things, it's fantastic.
    Whenever I have a doubt, you clarify it in the very following sentence!

    • @jbstatistics
      @jbstatistics  3 роки тому +2

      Thanks for the kind words!

    • @ojussinghal2501
      @ojussinghal2501 3 роки тому +2

      @@jbstatistics You're welcome. I'm studying probability and statistics as a first-year student and your videos are helping out a great deal!

  • @roh_yinee5229
    @roh_yinee5229 7 років тому +47

    My uni professor made this topic so confusing I got frustrated thinking I'm too dumb. But this vid explained it so well. Thank you Sir.

    • @jbstatistics
      @jbstatistics  7 років тому +2

      I'm glad to be of help!

    • @黎銘-s9n
      @黎銘-s9n 3 роки тому +4

      It's my personal observation that professors are good at making simple facts complicated, which is precisely why parents pay the high tuition. They make an image of authority of something for themselves in front of learner by making easy problems difficult.
      People pay doctors generously when they are in severe pain, which is in the same blind spot of human nature.

    • @thvbitch
      @thvbitch Рік тому +1

      ​@@黎銘-s9n exactly well said

  • @Bitrey
    @Bitrey 3 місяці тому +1

    Sir thank you so much. No need for fancy university documents with so much theory and no examples, THIS is how you teach, so so clear.

    • @jbstatistics
      @jbstatistics  3 місяці тому

      Thanks for the kind words! I'm glad to be of help.

  • @quaemeany
    @quaemeany 11 років тому +13

    This is honestly better done than Khan Academy. You seem to know what you're going to say rather than winging it like he does in every single video.

    • @jbstatistics
      @jbstatistics  11 років тому +17

      Thanks Lake. I try very hard to be concise while still being true to statistics. I don't like to waste anybody's time, so I try to keep these videos short and to the point.

  • @subconcioussplatter
    @subconcioussplatter 9 років тому +7

    This is great. All the explanations are concise and I like that you clarify certain things so that you don't fall in to the typical traps. Thanks for the stats video, I can finally understand it :)

  • @ExactusAtelier
    @ExactusAtelier 2 роки тому +3

    Here I am as a graphic designer watching a video about expected value yet found it way more entertaining than any business calculus course I took in college. Thank you 😂

  • @amritsharmapoudel959
    @amritsharmapoudel959 5 років тому +1

    The way you focus on the important points with your voice is just awesome! Likes! You are the real MVP.

  • @Pastozafaire
    @Pastozafaire 2 місяці тому +2

    Pure Brilliance! Well done! You are a GENUIS!!!

    • @jbstatistics
      @jbstatistics  2 місяці тому +2

      Not a genius, but glad I could help :)

  • @jbstatistics
    @jbstatistics  11 років тому +1

    You are very welcome! I'm very glad you are finding my videos helpful. And thanks for the compliments!

  • @aditipatil9491
    @aditipatil9491 5 місяців тому +4

    You made it effortlessly easy to understand 😀
    Thank you!!!

  • @roseroast527
    @roseroast527 4 роки тому +3

    Thanx man... I'm from India... There will be my exams in 3 days and this question here was the only one from whole probability of our syllabus that I wasn't able to understand... Now u explained it in a really beautiful way...

  • @hadidy13
    @hadidy13 Рік тому

    This is by far the best explanation I've ever watched!

  • @RononDex35789
    @RononDex35789 7 років тому

    I love you so much. i have been trying to figure out my professors notes and lecture slides for over 2 hours. you are an angel!!!!

  • @426rls
    @426rls 10 років тому +5

    This is so helpful- you are great at explaining things clearly without moving too slowly. Love your videos!!

  • @applejuice69.
    @applejuice69. 2 місяці тому +1

    Im gonna cry UA-cam teachers like you make me realize I'M NOT STUPID my stats professor explained this in a way that I couldn't understand at all and i felt like such an idiot cause everyone else seemed to get it thank you SO much!!❤️❤️

  • @jasmeet17mast
    @jasmeet17mast 9 років тому +15

    Very clear.
    Video and audio quality is good too. Thanks for sharing

    • @jbstatistics
      @jbstatistics  9 років тому +1

      +Jasmeet Singh You are very welcome! Thanks for the compliment!

  • @babangidaomolos5104
    @babangidaomolos5104 7 років тому +1

    what took a semester to understand has been accomplished in less than 8 minutes!
    amazing....

  • @RenadAdel-og5bs
    @RenadAdel-og5bs Місяць тому +1

    this was 12 years ago, OMG, and here I am, reaching out to it 12 years later thank you, man

  • @jbstatistics
    @jbstatistics  11 років тому +12

    Thanks! Other than 1 year in Georgia, I've lived in Ontario my whole life, and near Toronto for the last 20 or so. But in the last 6 months or so, 4 people have asked me about my accent in face to face conversations. So people are hearing something, but I don't know what it is. I have a tendency to use secondary pronunciations of words that are a little softer than the primary pronunciation. But maybe it's just the small town Northern Ontario Kenora boy showing through :)

  • @yoxiyogaming
    @yoxiyogaming 5 років тому

    This is AMAZING. In this 8minute of video, I learn more than 2 weeks of material

  • @Daniel-aaaaa
    @Daniel-aaaaa 2 роки тому +1

    I keep looking back at these videos, and there is no better channel than this one. One decade later and it's still high quality. Only downside is that stats and probability is such a broad topic and you're only one person, so coving all of it is impossible 😔

    • @parleymanderson7490
      @parleymanderson7490 2 роки тому

      Yeah, I can’t imagine that the 1-and-a-half-hour long lecture from my university can be shortened to 7 minutes and become much easier to be understood.

  • @BoZhaoengineering
    @BoZhaoengineering 4 роки тому +1

    one of the best interpretation of expected value and variance! definitely.

  • @jbstatistics
    @jbstatistics  12 років тому +5

    You're welcome Laura, I'm glad you like them!

  • @chuckn11
    @chuckn11 10 років тому

    I just want to say to this guy thank you so much, you really take the time to explain what each little detail means. Ok back to learning.

    • @jbstatistics
      @jbstatistics  10 років тому

      You are very welcome. I hope my videos help you learn a lot! Cheers.

  • @TheArnoldification
    @TheArnoldification 6 років тому +4

    Thank you. These videos are very well made and easy to follow. I like my prof but he tends to cover proofs and theory a lot and can be rather difficult to follow sometimes, so these are very helpful for clarification.

  • @jianxiongji2578
    @jianxiongji2578 8 років тому +5

    i have spent tons of time on this topic and this is by far the most helpful one. Thank you so much!

  • @kalcivar5
    @kalcivar5 4 роки тому

    Thank you, Thank you, Thank you! for your clarification at the beginning of the video! I spent a day trying to understand the book to then watch this video and understand in 8 minutes!

  • @yummymummy123456
    @yummymummy123456 9 років тому +14

    Thank you, it is such a relief to figure this one out. I still have some hair left on my head!!

    • @jbstatistics
      @jbstatistics  9 років тому +4

      +Peta King You are very welcome!

  • @89Valkyrie
    @89Valkyrie 5 років тому

    My professor explains it just like this, just as fast. This is a great refresher. Thank you for the video.

  • @Satya-chowdhury
    @Satya-chowdhury 2 роки тому

    You summed up the full chapter in 7 minutes. And understandable way

  • @alena6223
    @alena6223 9 років тому

    Thanks for actually explaining things. Makes so much more sense now.

    • @jbstatistics
      @jbstatistics  9 років тому +1

      +Alena Foresterun You are welcome. I'm glad I could help!

  • @sssssssssss231
    @sssssssssss231 3 роки тому

    Excellent teaching,every thing is going straight into head,no doubts at all,thank you

  • @melindabaye439
    @melindabaye439 4 роки тому

    a BIG thank you to JB everything is so clear it is very helpful

  • @jbstatistics
    @jbstatistics  11 років тому +3

    You are very welcome bugs! I'm happy to help out.

  • @faustin289
    @faustin289 4 роки тому

    I enrolled to an inference statistics course on Coursera.org and couldn't wrap my head around this module. Thanks for saving me!

  • @garrylove8955
    @garrylove8955 2 роки тому

    My lecturer is useless and it's driving me nuts. I did this stuff when I was 16 and somehow he's managed to make it complicated. Thanks for the refresher. Wish me luck.

  • @Brinx101
    @Brinx101 10 років тому

    I love you mister. I've been having trouble with this for hours until i stumbled across your video. Thank you

  • @cyto4335
    @cyto4335 2 місяці тому +1

    11 years later and still saving lives 🙏🙏

  • @jbstatistics
    @jbstatistics  11 років тому +2

    You're very welcome! And thank you very much for the compliment!

  • @faseg1000
    @faseg1000 9 років тому +1

    This is a great job. Well explained and cleared all my doubts and confusion.

  • @beefandpotatoes6525
    @beefandpotatoes6525 4 роки тому

    as usual very organized, well explained, and with right speed.

  • @landonchan7429
    @landonchan7429 6 років тому

    TY JB! Ur straight up saving our grades out here. God bless!

  • @steaKnife
    @steaKnife 7 років тому

    Been struggling with PMFs for a while now, and in under 8 mins he has gone and made it crystal clear!

  • @mjitape2083
    @mjitape2083 11 років тому

    Best Statistics lecture I've ever heard....this is perfect...thank you sir!!

  • @aymanadam7825
    @aymanadam7825 5 років тому

    Thanks a lot!! You explain it way better than my professor in the university.

  • @clemiboi
    @clemiboi 11 років тому +1

    thanks. you've helped me understand points which i couldnt in a 1.5 hour lecture.
    more can be emphasized on the meaning of the the expected value and how it contrasts with the actual mean.

  • @timothyr.pachuau4878
    @timothyr.pachuau4878 5 років тому

    So much more helpful than our lecturer....thank you

  • @HackyTV
    @HackyTV 11 років тому +3

    Thanks. This is a great video; really compact and well organized.

  • @djcinetic
    @djcinetic 4 роки тому +5

    Perfect! but how did you find the 0.16, 0.48, 0.36 probabilities? are these just random example values?

    • @BasilBabar1
      @BasilBabar1 Рік тому +8

      From the given statement we know that 60% of the people approve the president. In other words probability of choosing a random person who approves the president is 0.6. Conversely, the probability of choosing a person who disapproves of the president is 0.4
      - X=0 means that choosing two people who disapproves the president. Therefore 0.4*0.4=0.16
      - X=2 means that choosing two people who approves the president. Therefore 0.6*0.6=0.36
      - X = 1 means one person disapproves while other approves. Therefore 0.6*0.4*2 = 0.48 ( I multiplied it by 2 bcz there are 2 possible combinations i.e. either the first person approves and second disapproves or the first disapproves and the second approves)
      The main assumption over here is that choosing a person from the population doesn't change the probability distribution considering the sample size is large. Had it been a case where the sample size was small then we had to redefine the value of probability while choosing the second person.
      Hope it helps!

    • @houston8713
      @houston8713 Рік тому +1

      @@BasilBabar1 goated

  • @jbstatistics
    @jbstatistics  11 років тому +2

    You're welcome! I'm glad to be of help!

  • @coreychen3374
    @coreychen3374 3 роки тому

    watching this in 2021 before my midterm. thanks jb!

  • @HalorRacer
    @HalorRacer 9 місяців тому +1

    If only my teacher could teach like this man

  • @Zoni-arain
    @Zoni-arain 10 місяців тому +2

    This is so good and I am watching this in 2024.

    • @jbstatistics
      @jbstatistics  10 місяців тому +1

      Not much has changed in this topic :)

  • @amindehbokri2259
    @amindehbokri2259 6 років тому

    JB you are my hero for saving me before my exam tomorrow

    • @jbstatistics
      @jbstatistics  6 років тому

      I'm glad to be of help! I hope your exam went well!

  • @nidhimathew9848
    @nidhimathew9848 4 роки тому

    Thank you so much for explaining this so well. This was bugging me for a really long time.

  • @jessicajiang139
    @jessicajiang139 6 років тому

    Just want to say thank you. Super easy to understand.

  • @jbstatistics
    @jbstatistics  11 років тому +1

    You're welcome! And thanks for the compliment!

  • @kunbuzo6510
    @kunbuzo6510 3 роки тому

    Thank you sir you are 100x more helpful than my probability professor

  • @virnan
    @virnan 5 років тому

    This is done really well sir. You explain in not too technical language.

  • @chrishoman4521
    @chrishoman4521 8 років тому

    great video! understood the work clearly after watching this video.

  • @christianbouwense4702
    @christianbouwense4702 8 років тому

    Perfect, this is exactly what I was looking for and desperately needed. Thanks!

  • @ng9080
    @ng9080 2 роки тому

    bless your videos, wow. You're saving me big time.

  • @ysbeautyinc
    @ysbeautyinc 10 років тому

    This video was so simple and so helpful, great job! Much appreciated.

    • @jbstatistics
      @jbstatistics  10 років тому

      Thanks! I'm very glad to be of help.

  • @adassyposz3699
    @adassyposz3699 2 роки тому

    Cheers mate, I'm cramming for my a-level further maths mock, and this has come in really useful.

  • @Mbc43m276
    @Mbc43m276 7 років тому

    Thanks JB. Would have been impossible understanding this without the video

  • @pheonix1461
    @pheonix1461 3 роки тому

    Thank you so much for making it easier to understand, my teacher uses a lot of terms that I don't even know what's happening lol.

  • @wasimsaliby6720
    @wasimsaliby6720 3 роки тому

    Great review material for the FE Exam, thanks a lot!!

  • @preetirajput2414
    @preetirajput2414 6 років тому

    Thank you for this video...I badly needed this method.... thanks a ton.... God bless you

  • @rishabhnarula1999
    @rishabhnarula1999 Рік тому +1

    great teaching sir, thanks.👍😊

  • @avivran1198
    @avivran1198 4 роки тому

    {RV - Random Variable}
    On video time 0:50 - the lecturer says something that sounds unclear (not to say wrong)
    "The expected value of an RV is a parameter, not a statistic"
    An RV variable outcome is based on sample space (which is where statistic only is calculated)
    All sample space calculated values including frequency, relative-frequency(=porbability) are all statistic
    The probabilities associated with an RV outcome are part of the statistic, hence the expected value E(X)
    is a statistic (for sure not a parameter, as a parameter is related to the POPULATION)
    I'll be glad to have the lecturer comment on that ...

    • @garrondumont
      @garrondumont 4 роки тому

      "An RV variable outcome" Uhm, RAS syndrome?

  • @enkapo
    @enkapo 7 років тому

    A brilliant piece of work! Thanks!

    • @jbstatistics
      @jbstatistics  7 років тому

      You are very welcome. Thanks for the compliment!

  • @shobhitmundhada3315
    @shobhitmundhada3315 2 роки тому

    I was stuck on the variance part of the question, and I appreciate your help.

  • @kartikanand5374
    @kartikanand5374 4 роки тому

    Thanks a lot! Your words were really precise. That helped a lot!

  • @Leo_Nader
    @Leo_Nader 6 років тому

    Incredibly helpful. Thanks a bunch.

  • @jbstatistics
    @jbstatistics  11 років тому

    Thanks! I'm glad you liked it.

  • @rebekahm6672
    @rebekahm6672 Рік тому

    Thank you, this made it easier to understand

  • @SolosisterN
    @SolosisterN 11 років тому

    Thank you for this video so much easier to understand than the lecture notes :-)

  • @rajamoorthy1969
    @rajamoorthy1969 Рік тому +1

    Great explanation. Thanks

  • @parvejmahmud1740
    @parvejmahmud1740 3 роки тому

    Very helpful these days too.

  • @schinoda
    @schinoda 9 років тому +1

    You should make more math videos. This topic just became a breeze in less than 8 minutes. Gracias! :)

    • @jbstatistics
      @jbstatistics  9 років тому

      +Kelvin Mwangi You are welcome Kelvin! I'm glad you found this helpful. I'll find some time to make more videos at some point.

  • @minhtien7919
    @minhtien7919 4 роки тому

    8 years later and still find this useful

  • @baiqinglyu4254
    @baiqinglyu4254 4 роки тому

    This guy is saving my class, can I pay you the tuition instead

  • @CascadeTwelve
    @CascadeTwelve 2 роки тому

    Really clear and concise. Thank you!!

  • @derekwang9226
    @derekwang9226 2 роки тому +1

    Is there a proof for the formula at 2:58?

  • @cjs3298
    @cjs3298 6 років тому

    Really am very clear with your definition, thanking you sir

  • @xanderlewis
    @xanderlewis 7 років тому

    Brilliantly explained. Thank you.

  • @hamayunkhan2287
    @hamayunkhan2287 9 років тому

    Thank you. You saved my life!!!

  • @adtkr
    @adtkr 9 років тому

    Amazing Narration.... Greatly done

  • @trestenpool9045
    @trestenpool9045 4 роки тому

    Great freaking vid man. Helped out a ton!

  • @EHBRod13
    @EHBRod13 9 років тому

    I love you! Your videos are phenomenal!

    • @jbstatistics
      @jbstatistics  9 років тому

      +Brandon Rodriguez Thanks! I'm glad to be of help.

  • @jsc0625
    @jsc0625 2 роки тому

    Extremely helpful, thank you!!

  • @bugsbunny5661
    @bugsbunny5661 11 років тому

    Cant thank you enough for posting such amazing videos :). Thank u thank u thank u thank u soooooo much

  • @flicktionofficial
    @flicktionofficial 8 років тому

    JB, how do we interpret the results (mean and standard deviation) of a given problem on discrete probability distribution? How do we compare the mean and standard deviation?