Recent content by obh

  1. O

    ANOVA on three columns?

    You should calculate the test power before running the ANOVA test, based on the effect size you want to identify. Running Tukey HSD will not give different accepted/rejected results, in your specific case correct alpha is 0.00166 and Group2-Group3 p-value is 0.01558. But if the p-value was...
  2. O

    ANOVA on three columns?

    It reduce the alpha too much. Hence you may not reject incorrect h0. Usually there is no pure independency between the columns.
  3. O

    ANOVA on three columns?

    Hi Nik, If it meets the ANOVA assumptions it should be okay. But the Bonferroni correction is too conservative. It is usually better to do the Tukey HSD test.
  4. O

    Fisher's exact test for this table?

    Since the sample size is large it is obvious to me ...that the is a significant association between height and species. But you should run the test to make it quantitative, otherwise, in some cases, people will decide "it is obvious" and it won't be correct ...
  5. O

    ANOVA on three columns?

    Hi Nik, You mention the time. Are the observations independent? Does the result of 10 seconds depend on the 9 seconds result?
  6. O

    Is this a regression?

    Hi Neke, Do you have only 4 rows of data?
  7. O

    Probability of dying from Covid today

    Without checking your numbers, It is more complicated ... I can assume that the percentage of vaccinated people is higher in the high-risk population. You should also take into consideration all the people that recover from the covid, symptomatic and asymptomatic, they are vaccinated at least to...
  8. O

    [R] - Test to say if I can accept or not my data in a right-skewed distribution

    How many people/groups do this fix? internal or external to your organization? You may find from your fix data the 99% percentile (or 99), meaning in 99% of the fixes the time is less than this value. but in this case, on average 50 times (0.01*5000), the fixed time will be larger. You may...
  9. O

    Kruskal-Wallis, Dunn's Test, Multiple Mann-Whitney-U Test

    Hi AC, I don't have the knowledge about the distribution of the immune cells ... The one way ANOVA considered to be robust to the deviation from the normality assumption I would try to draw the histogram of the data, and if it is reasonably symmetrical I would use the ANOVA. You may use the KW...
  10. O

    Kruskal-Wallis, Dunn's Test, Multiple Mann-Whitney-U Test

    The Kruskal-Walis with two groups is the same as Mann-Whitney-U (maybe only a different approximation for the result or not) If you use multiple testing you should consider reducing the significance level. Yes, it is okay to apply multiple MWU tests after K-W, as you ask a different question ...
  11. O

    Stats help - please!

    I assume you relate to the first example I wrote ( compare two drugs A and B) In this case, drug B might be better than A, or worse. So clearly you should use the two-tailed approach. But in the current example, as I understand the question, I assume that the treatment might only improve the...
  12. O

    Stats help - please!

    Hi @hlsmith :) It probably won't be normal... at least the placebo treatment. I thought only of the treatment. But the best way is to look at your data ... Correct if you are not sure, it is better to be cautious and use the two-tailed approach. If you compare two drugs A and B and you try to...
  13. O

    Stats help - please!

    The difference between one tail and two tails is big, as in one tail the significance level is only on one side of the distribution. so it likes a two-tail with a double significance level. If you are clueless about how the treatment will influence you should use the two tails. But if you have...
  14. O

    Stats help - please!

    So this is only one direction, meaning one tail. If H1 will be that the treatment changes the time (for good or for bad) you would choose the two tails, but this Is not the case. What is the sample size? Does the time distribution is normal? symetrical?
  15. O

    Stats help - please!

    What is your alternative hypothesis (H1)? I would assume that you expect the treatment to reduce the "time to onset of pain relief"?