Welch (Unpooled Variance) t Tests and Confidence Intervals: An Example

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  • Опубликовано: 23 окт 2024

Комментарии • 20

  • @stephenkrafcik8643
    @stephenkrafcik8643 11 лет назад +2

    Incredible videos man, I can't thank you enough for doing this. I have a midterm tomorrow, but I've been going through all your videos and feel entirely prepared.

    • @jbstatistics
      @jbstatistics  11 лет назад +1

      You are very welcome Stephen. I hope you learned a lot, and I hope your exam goes very well!

  • @한도흔-k5w
    @한도흔-k5w Год назад

    You saved my day. Appreciate it 😊

  • @m.bouanane4455
    @m.bouanane4455 2 года назад

    Thanks for the insightful videos.
    What does mean when SEw = SEp?
    Does it mean that it is likely Sigma1 = Sigma2 ?

  • @jbstatistics
    @jbstatistics  11 лет назад

    To test the null hypothesis that the population means of several groups are all equal, we often use one-way ANOVA. If this gives strong evidence of a difference in population means, then we may investigate all the pairwise combinations. That's the gist, but there's much more to it than I can do justice in a short response. I have several videos on one-way ANOVA. Cheers.

  • @myrtogerakari6511
    @myrtogerakari6511 2 года назад

    Hi- amazing video, thanks for sharing. Could you please explain how I found the P value for two-tailed without software?

  • @rajjain7628
    @rajjain7628 4 года назад

    You can also find d value instead of p it will be more helpful? To know the treatment effect

  • @patrickkelly7821
    @patrickkelly7821 5 лет назад

    I love this! thank you so much!!!

  • @bennettturk3206
    @bennettturk3206 11 лет назад

    What if the means of more than two groups are compared? Do we just check every combination?

  • @badguy66626
    @badguy66626 7 лет назад +11

    im doomed

  • @mesifli
    @mesifli 9 лет назад

    you are the man!!

  • @Squidward104
    @Squidward104 6 лет назад

    Sooooo, long story short: the only difference between t-test and welch t-test is the formula for the degrees of freedom, right?

    • @jbstatistics
      @jbstatistics  6 лет назад +8

      Sooooo, long story short: the only difference between London and Paris is that one is in England and the other in France, right?

  • @seanv4779
    @seanv4779 7 лет назад

    Why is .025 2.228? If you use invnorm it is 1.959 what am I doing wrong?

    • @jbstatistics
      @jbstatistics  7 лет назад +2

      You're finding the 97.5th percentile of the standard normal distribution, but we need to find it for the t distribution with the appropriate degrees of freedom.

  • @seanv4779
    @seanv4779 7 лет назад

    Why don't you actually show how to find the degrees of freedom. That is the hardest one.

    • @jbstatistics
      @jbstatistics  7 лет назад +3

      I wouldn't call that part hard, as it's just jamming numbers through the formula. I don't typically make my students carry out that calculation, as we typically rely on software, so I don't work through the formula here.

  • @Faith_30
    @Faith_30 5 лет назад

    too complicated to understand ..

    • @jbstatistics
      @jbstatistics  5 лет назад +1

      It's as complicated as it needs to be, and understandable. I don't expect everybody to be able to understand everything on first viewing, and some concepts might require some thinking and rewatching.