I describe the background to the Bonferroni correction (type 1 error and familywise error) as well as the two approaches to conducting a Bonferroni correction.
hi, thank you for the video!!-.recently I read a trial that calculates the relative risk fo two procedures but the result is lower than you would expect (I used epi info to calculated with IC). the authors mentioned that they used the Bonferroni correction. Could this difference be related to Bonferroni´s correction?
Hello I am comparing gene expression data between two groups (control and diseased) and have to test seven genes.... for each gene the CT values are different for each group. I have used Mann Whitney U test. The sample size is small, Diseased: 16 and controls: 8. Kindly please suggest I need to do the correction test for the observed p values for each gene or not?
Hello, thank you for the video! What if I conduct one-way ANOVA between a,b,c groups on y variable and then regression with a/b/c groups on and some other parameters on z variable, shall I correct the analysis P value,since technically a,b,c are used in both tests?
Thanks for this nice and easy-to-follow tutorial. I have questions... I compared whether Group 1 is smaller than Group 2. To get the data for this comparison, I used a formula with two parameters to play around. Let's say, I have 12 sets of data for comparison, i.e., G1 vs. G2 using scenario #1, G1 vs. G2 using scenario #2, ..., and G1 vs. G2 using scenario #12. I don't want to compare which parameter combination is the best. The main goal is to test if G1 < G2. Should I use Bonferroni correction?
I have a follow up question. I conducted a within group study where all participants performed 3 variation of a task. At first, I ran Friedman's ANOVA and found statistical significance. Secondly I ran wilcoxon signed rank test between two of the three variations. I did it twice (according to my initial hypothesis) between variation A and B and between A and C . So should I divide the p value by 3 for all the three tests? I mean the p values from friedman ANOVA, and two wilcoxon tests. Thanks in advance for your reply
In my (free) textbook (www.how2statsbook.com), I provide support (references) for not doing a correction, if you have only three levels associated with your factor and the omnibus statistic is significant, like your case. It's in chapter 7 and chapter 16,
SPSS does not do it automatically outside of ANOVA. You can either divide your alpha by the number of t-tests and compare your obtained p-values against that adjusted alpha level; or, you can multiply the obtained t-test p-values by the number of t-tests you performed and declare any of the multiplied p-values less than .05 as significant statistically.
Great video, thanks! I have a follow-up question. What happens when there are multiple comparisons but not on the same sample of data? For example, when two groups (control, treatment) are compared across several outcome measures (e.g. language, memory, attention, behaviour, etc.). In this case you run multiple comparisons but not on the same sample each time. Does this require correction as well? Thanks!
The Bonferroni correction is an adjustment made to P values when several dependent or independent statistical tests are being performed simultaneously on a single data set. Please explain what is the meaning of single data set there....
It means that a person conducts several different statistical analyses with the same sample of data. For example, a researcher might conduct 5 correlations and 3 t-tests with the same sample of data (that includes several different variables).
Hi, Suppose I have a customer level dataset and each customer belong to a segment and I have to calculate the uplift for each segment using Anova. Now, I want to understand the application of Bonferroni correction - since I will be performing Anova for each segment seperately, do I need to apply the correction or not? What I think is since the customer base for each of the segment is mutually exclusive we don't need to apply it. Please let me know what should be actually done.
Amazing! Now it's clear to me. I am using pairwise.wilcox.test in R with Bonferroni correction and it's using the second approach. but unfortunately, I can't find a reference to talk about this approach. could you please provide a reference for the citation of the second approach?