An Introduction to the Permutation Test

แชร์
ฝัง
  • เผยแพร่เมื่อ 29 ต.ค. 2024

ความคิดเห็น • 58

  • @ugururesin8405
    @ugururesin8405 6 ปีที่แล้ว +19

    As a PhD. student, I have seen hundreds of videos related statistics and this is one of the excellent ones!
    Thanks in advance!

  • @real.biswajit
    @real.biswajit 2 ปีที่แล้ว +1

    Thank you so much for the video. It's far better than the others videos on TH-cam. This made easier to understand the permutation test. You are a very good teacher and explainer.❤️

  • @jtabuti
    @jtabuti 4 ปีที่แล้ว

    This has been very well presented. For a non-statistican like me it has erased a lot of agony.

  • @StephenHsiang
    @StephenHsiang 6 ปีที่แล้ว

    this is a very good and clear explanation of the idea. I wish I could have watched this first, then half an hour of watching another one could be saved.

  • @GbUnLimiteD
    @GbUnLimiteD 5 ปีที่แล้ว

    Excellent tutorial! I really like the approach to not only explain what a permutation test is but compare it to the t-test. I often struggle when people just present you another test amongst hundreds of other ones but then do not explain why this particular test could be better or worse than the other.

  • @getchrismo
    @getchrismo 3 ปีที่แล้ว

    Thanks Lloyd, great explanation for us non-statisticians

  • @WA-hq6ls
    @WA-hq6ls 4 ปีที่แล้ว +1

    man, this video, man, man, man thank you!

  • @sosaysmrstewart
    @sosaysmrstewart 7 ปีที่แล้ว

    Thank you for this video! For some reason I just couldn't understand what permutation testing was about - turns out its very simple. Great demonstration.

  • @tonynikolaos3527
    @tonynikolaos3527 2 ปีที่แล้ว

    Bravo! Big Thanks for the best explanation ever!

  • @edanwang4805
    @edanwang4805 5 ปีที่แล้ว

    Thank you for explaining permutation test so easy to understand!

  • @sarahwoolston4421
    @sarahwoolston4421 8 ปีที่แล้ว +1

    Thank you so much! You have no idea how much this has helped me.

  • @jlpicard7
    @jlpicard7 9 ปีที่แล้ว

    Nice job explaining the concept with this simple example. Thanks for creating this video.

  • @joannitsious
    @joannitsious 4 ปีที่แล้ว

    Great job!! Thank you so much for explaining everything in a simple and straightforward way :)

  • @letthewolvesin6345
    @letthewolvesin6345 4 ปีที่แล้ว

    Thanks Lloyd, the app is a great visualisation

  • @ngeetha1553
    @ngeetha1553 4 ปีที่แล้ว

    easy way to understand and thank you so much

  • @DataTranslator
    @DataTranslator 7 หลายเดือนก่อน

    This was extraordinary 🎉

  • @spiritumsantorini
    @spiritumsantorini 9 ปีที่แล้ว +1

    Now that's easy. Great program. Thanks Lloyd!

  • @binusharma3590
    @binusharma3590 3 ปีที่แล้ว +1

    Thank you for the video. I have a question does the permutation test work with repeated data.

    • @lrieber
      @lrieber  3 ปีที่แล้ว +1

      Interesting question. To be honest, I don't know. My hunch is that it does apply to any test of statistical significance. Thanks for your question.

  • @jianzhangni4361
    @jianzhangni4361 3 ปีที่แล้ว

    Very helpful! Thank you!

  • @andreaLA222
    @andreaLA222 3 ปีที่แล้ว

    Great video! Thanks!

  • @nicnahar6273
    @nicnahar6273 4 ปีที่แล้ว

    Great explanation, much appreciated content!

  • @mlbdenver1
    @mlbdenver1 8 ปีที่แล้ว

    Excellent simple explanation. Thank you!

  • @EricWajnberg
    @EricWajnberg 8 ปีที่แล้ว +4

    Well done, but..: The assumption of a standard t-test is indeed to have random samples and random assignment, but - on the contrary to what is said here - a permutation test is also based on such assumptions. If there is a bias due to non-random samples and/or assignment, such bias will remain with a permutation t-test. So, why bothering with permutation tests? Actually, a standard t-test also has a number of other assumptions, i.e., the measured scores must follow normal distributions and the variances of the two samples must be equal. If this is the case, then the distribution of the t-value is known. It follows a Student distribution. This is not the case any more with a permutation test and the distribution of the test (here the difference between the two means) is estimated empirically as explained in the video, giving an estimate of the p-value. In other words, permutation tests can be a good choice (among others) if the traits measured is not following a normal distribution and/or if the variances of the two samples are not equal. In this respect, the way things are explained in the video are somewhat misleading.

    • @lrieber
      @lrieber  8 ปีที่แล้ว +5

      Eric, thank you for your comment. I hope my video is not misleading or mistaken on the point you make. I don't think it is. The point, made by George Cobb (whose article I used to guide my video), is that the permutation test is a much better fit for the reality of the data set presented in the video. As you point out, the t-test has several important assumptions, such as a normal distribution with equal standard deviations. Cobb (2007) writes regarding the hypothetical example used in the video: "Notice that because the set of observed values is taken as given, there is no need for any assumption about the distribution that generated them." Hence, there is no assumption of normality or equal variances. The data were from a convenience sample, and not randomly drawn from a population. But, the people were randomly assigned to the treatment or control. Again, thanks for your comment - it gave me a good reason to go back and reread the Cobb article (it's listed in the references at the end of the video).

  • @ameyjain3462
    @ameyjain3462 3 ปีที่แล้ว

    I have seen reports with permutation rank as well, what does that tell us about the permutation test?

  • @lmakrakis
    @lmakrakis 6 ปีที่แล้ว

    Great explanation! It´s all very clear now!

  • @alexmarti6014
    @alexmarti6014 6 ปีที่แล้ว

    This is simply perfect, thanks!

  • @julietannetaglucop5763
    @julietannetaglucop5763 4 ปีที่แล้ว

    Thank you so much for very useful video. However I just want to clarify. I was confused with the 'repeat'. I initially thought it pertains to the permutation value which was for your example was 35. But later on you assigned 5000 counts on it. Do you just randomly chose amount of repeat? Thanks

  • @manuelargos
    @manuelargos 3 ปีที่แล้ว

    EXCELENTE!! Muchas gracias

  • @tatianaizmaylova9739
    @tatianaizmaylova9739 6 ปีที่แล้ว

    Fantastic explanation! Thank you!

  • @zimyang4852
    @zimyang4852 7 ปีที่แล้ว

    Really awesome explanation!

  • @timothyleung5663
    @timothyleung5663 4 ปีที่แล้ว

    Lloyd, I have a concept I'd really like to clarify before my exam next Wednesday. My prof, unfortunately, isn't capable of understanding the core of my question. If we are to rearrange the groupings but the order of the cluster, i.e., person A-G here, doesn't matter, are we not counting combinations? Why is it called a permutation test?

  • @inigoaraluce8493
    @inigoaraluce8493 2 ปีที่แล้ว

    This helped a lot!

  • @gttabor
    @gttabor 3 ปีที่แล้ว

    It seems the equation you provided for # of permutations is actually the equation for # of combinations?

  • @jordia.2970
    @jordia.2970 3 ปีที่แล้ว

    Great video indeed

  • @dewinmoonl
    @dewinmoonl 2 ปีที่แล้ว

    this is just great. thanks for this, the app is cute!! and the explanation is good

  • @lucydavis6371
    @lucydavis6371 4 ปีที่แล้ว

    Thanks this really helped!

  • @abrahamdelgadilloramirez7503
    @abrahamdelgadilloramirez7503 5 ปีที่แล้ว

    excelente video!!!

  • @fouadsel88
    @fouadsel88 7 ปีที่แล้ว +1

    Thank you

  • @johnk8174
    @johnk8174 7 ปีที่แล้ว

    Very nice. Thank you.

  • @masih3184
    @masih3184 8 ปีที่แล้ว

    Is there anyway to use permutation for categorical data?
    For example if I have 1000 samples into 4 categories A to D in one population and another 1000 samples from population B, could I use permutation test to measure if Group A and Group B are significantly different?

    • @lrieber
      @lrieber  8 ปีที่แล้ว +1

      Interesting question. I'm not really sure, but I don't see why not. I suggest you read the articles by Cobb and Ernst. The article by Ernst is much more technical in nature and may address your question directly.

  • @helenhelen974
    @helenhelen974 6 ปีที่แล้ว

    brilliant. thank you.

  • @debjanibhowmick4719
    @debjanibhowmick4719 6 ปีที่แล้ว

    A perfect teacher.:)

  • @llinuxer
    @llinuxer 3 ปีที่แล้ว

    Thanks for the great video and explanation
    In reference to: th-cam.com/video/GmvpsJHGCxQ/w-d-xo.html: One of the reasons you are getting a slightly larger p-value than the author (in the referenced paper) is because you are essentially conducting a two-tailed test by computing the absolute mean difference and comparing to observed mean difference of 9. In the paper, the author conducts a one-sided test and compares the mean differences to the observed mean difference of -9. Thus, the p-value obtained in the paper is a one-sided left-tailed p-value while yours is a two-sided p-value which is slightly higher. I hope this helps.

    • @lrieber
      @lrieber  3 ปีที่แล้ว

      Thank you for this comment. This is very helpful. I intend to reread the referenced paper. If you are correct, that would explain the difference very well. Much appreciated! Lloyd

  • @stevenlam4133
    @stevenlam4133 6 ปีที่แล้ว +1

    Wouldn't the formula shown be referring to combinations and not permutations?

    • @NotesFromPittsburgh
      @NotesFromPittsburgh 6 ปีที่แล้ว

      I have the same question.......anyone?

    • @OlegZendel
      @OlegZendel 4 ปีที่แล้ว

      Yes, the formula is for number of combinations, not permutations. Practically it doesn't matter (though I agree that it is misleading to say that the formula calculates the number of permutations), you can see an answer regarding this here: stats.stackexchange.com/a/304804/229802

  • @MartinLarsson
    @MartinLarsson 8 ปีที่แล้ว

    Could you link to the paper you're talking about, please?

    • @lrieber
      @lrieber  8 ปีที่แล้ว +1

      Here are the references shown on the final slide. I accessed the Ernst paper through the UGA library, but unfortunately I don't have copyright permission to share a link to that one. I hope you can access it through your library resources.
      Cobb, G. (2007). The introductory statistics course: A Ptolemaic Curriculum? Technology Innovations in Statistics Education, 1(1). Available Online: escholarship.org/uc/item/6hb3k0nz
      Ernst, M.D. (2004). Permutation methods: A basis for exact inference. Statistical Science, 19(4), 676-685.

    • @MartinLarsson
      @MartinLarsson 8 ปีที่แล้ว

      Thank you very much! I was able to access the Ernst paper through my university library.

  • @jiamingqu1644
    @jiamingqu1644 7 ปีที่แล้ว

    Thanks!

  • @Wanderlust1972
    @Wanderlust1972 ปีที่แล้ว

    Genius

  • @nithinma8697
    @nithinma8697 3 ปีที่แล้ว

    Permutaion formula is n!/(n-r)! not n!/(n-r)!r!
    Permutation = arrangement . here order of arrangement matters
    Combination formula is n!/(n-r)!r!
    Combination = selection. here order doesnot matter

  • @sauravgupta7415
    @sauravgupta7415 2 ปีที่แล้ว

    The permutation formula is wrong, that's a combination formula

  • @real.biswajit
    @real.biswajit 2 ปีที่แล้ว

    Thank you so much for the video. It's far better than the others videos on TH-cam. This made easier to understand the permutation test. You are a very good teacher and explainer.❤️