Signals situations where one is concerned about achieving intended power and size when more than one hypothesis test is performed.

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3
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3answers
214 views

Do I need to correct for multiple hypotheses? p-values all go to one

I have two groups, C and A, where C is control. In both groups there are about 3,000 proteins. For each protein we acquire six measurements in both C and A (these are mass spectrometry intensities by ...
0
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2answers
43 views

multiple significance testing of large data

I am doing analysis using multiple significance testing between about 20 parameters of data with >8000 rows. Since the number is reasonably large, even minor differences are coming with highly ...
0
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1answer
14 views

Correction of mutliple paired samples t-test

In one group of subjects I have four parameters (for e.g. A, B, C, D) measured in two conditions. I want to know whether these 4 parameters differ between the conditions by doing paired samples ...
1
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0answers
19 views

Tukey HSD, insignificant p-value when the confidence interval does not contain 0?

I am using TukeyHSD to do multiple comparisons. I am seeing strange results for some of the pairs: the adjusted p-value is greater than the specified significance level but the corresponding ...
0
votes
0answers
16 views

Multiple comparisons of proportions using complex survey data using SAS

I am interested in doing multiple comparisons of proportions using complex survey data in SAS. I can get estimates using proc surveyfreq or proc crosstab (using SAS-callable SUDAAN), but am not aware ...
1
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0answers
32 views

Comparison and testing multinomial coefficients

Straight to the problem I want to test the hypothesis that two coefficients of multinomial regression model are equal between them. For example, considering a model where Y is 3 level categorical ...
0
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1answer
45 views

How do I interpret a variance ratio test in Stata?

I need help with interpreting output from a Variance Ratio Test in Stata. $f = 1.2988$ (my variance) $\text{Degrees of freedom} = 249, 493$ I have Ho: ratio = 1 as my null Ha: ratio != 1 Am I ...
1
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1answer
34 views

Adjust the p-values or not?

This started as a simple discussion where everyone thought they new the answer, and ended up with arguments and dozens of paper quotations. Thoughts appreciated. We have 10 samples: Control, A, B, C, ...
1
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1answer
91 views

Multiple testing in correlation analysis over time periods

I have one variable measured once per time interval (say, once per year), and another variable measured periodically (say, once per day). The periodic measurements are autocorrelated. I am interest ...
0
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0answers
14 views

Comparing the difference in proportions for 3 different groups

I conducted an experiment and just need some general guidance on where to go from here. I know I have to do some kind of binomial test on my data. Suppose I have the following data: ...
0
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0answers
21 views

Multiple Comparison of Standard Deviations

I have a question about comparing multiple standard deviations: To start with, let's say I have calculated two standard deviations (s1, s2) from a series of random samples. If I want to determine ...
1
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0answers
18 views

get p value based on observed F and critical F

When conducting multiple comparisons, I can calculate a critical value via whatever method is appropriate for the situation. If the adjustment method I need is a common one such as Bonferroni, I can ...
0
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0answers
24 views

Do we need to correct p-values when using multiple models?

I am currently studying epidemiology. I am writing a paper that is examining 11 disease states in one species. I am using binomial logistic regression to examine 2 possible predictors (age and ...
1
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0answers
41 views

Estimating and comparing pre-post treatment effects in multiple pairs of treatment-vs-control groups

I have a dataset from an experiment where the goal was to study in which plant ecotype a treatment with a certain bacteria had the greatest effect. Hence the data consists of a number of control and ...
0
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0answers
4 views

Null distribution of the maximum and FDR control

Suppose we have a series of test statistics $T_{1},...,T_{m}$ each corresponding to a null hypothesis $H_{0}^{j}: \theta_{j} = 0$. Let $H_{0}: \theta_{1} = \ldots = \theta_{m} = 0$ denote the ...
1
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2answers
86 views

Any other non-parametric alternative to Kruskal-Wallis?

It looks like Kruskal-Wallis is the standard nonparametric test for more than two groups. The problem is that it does not tell which groups are different, except that whether there exists significant ...
0
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0answers
28 views

Rank sums in the Kruskal-Wallis output

I use Stata to perform a Kruskal-Wallis test on four groups of data (not normally distributed), and the results are shown below: ...
0
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0answers
11 views

how can i calculate square sum of all the products of the summation? [migrated]

Rule.  The square of a sum is equal to the sum of the squares of all the summands plus the sum of all the double products of the summands in twos: But I do not know how to calculate the square of ...
3
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0answers
99 views

How to best approach ANOVA with multiple response variables that might be correlated and Bonferroni Correction

I need some help verifying a simple analysis. I have completed a simple two factor experiment of more or less equal sample sizes. Let's assume for the case of this question that the sample sizes are ...
0
votes
1answer
55 views

Which post-hoc is more valid for multiple comparison of an unbalanced lmer-model: lsm or mcp?

After doing a model comparison with my mixed lmer model, I have a model with three main effects, no interaction, say ...
0
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0answers
28 views

How do I report the result of an mcp-Tukey-test, i.e. how do I report it's z value?

After doing a model comparison with my mixed lmer model, I have a model with two main effects, no interaction, say signal ~ factor A + factor B + (1|subj). Factor ...
3
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5answers
162 views

What's wrong with Bonferroni adjustments

I had read an article has this title "What's wrong with Bonferroni adjustments?" for Thomas V Perneger He summarized saying that Bonferroni adjustment have, at best, limited applications in ...
4
votes
1answer
62 views

What statistical test is performed by summary(glht(model, linfct=mcp(factor=“Tukey”)), test=adjusted(type=“none”))?

I have data that I have fit using lme with the following structure (Subject is implemented as a random effect in order to account for multiple paired comparisons): ...
1
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0answers
21 views

Multiple testing, alpha, and familywise error

I am confused why it is that in multiple testing, the expected number of false positives is: $$ \alpha \times\text{number of tests}\tag{1} $$ (That is, for $\alpha = 0.05$, you would expect $5\%$ ...
4
votes
2answers
67 views

Extent of multiple testing correction

A bit of a strange question. In my fourth year biostatistics class today, we were discussing when and when not to use multiple testing correction, and the professor made an offhand comment. He asked ...
0
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2answers
45 views

Do I struggle with multiple comparisons?

I know that if there is significant difference in means among groups in ANOVA, then one can perfrom post-hoc test ( Tukey HSD or something similiar) to get to know within which groups the difference ...
2
votes
2answers
38 views

Multiple models compared over same data

My question boils down to if I really have to use a multiple comparison adjustment or not, and if so, how I can do this to retain as much power as possible. I have multiple models (say 5) that are ...
3
votes
4answers
553 views

About the Bonferroni correction

I have 50 variables in my dataset. I have correlated each variable against each variable, thus I have $49·50/2 = 1225$ unique correlations when no variable is tested against itself. Now, suppose I ...
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1answer
44 views

How to test if many samples are from the same distribution

For each day of the week I observe $n_i$ independently chosen values from some process. I would like to be able to answer the following two questions. Are the distributions from which the samples are ...
2
votes
2answers
82 views

Should corrections for multiple comparisons be used when evaluating independent experiments?

I understand why corrections for multiple comparisons (e.g., the Bonferroni correction) are used in some cases. For example, if I run a a single experiment and check significance of many factors, the ...
0
votes
1answer
37 views

Multiple testing

I am regressing different dependent variables using same set of predictors for all dependent variables such as ...
0
votes
0answers
17 views

How to test differences in multiple pairwise distances? With mixed model?

I want to compare two set of variables: X1 = All the pairwise distances between individuals from group A and group ref R X2 = ALL the pairwise distances between individuals from group B and group ...
7
votes
0answers
110 views

Should we address multiple comparisons adjustments when using confidence intervals?

Suppose we have a multiple comparisons scenario like such as post hoc inference on pairwise statistics, or a multiple regression, where we are making a total of $m$ comparisons. Suppose also, that we ...
0
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0answers
10 views

post-hoc multiple comparisons with chi squared using spss v. 22

I am carrying out an analysis using a 4$\times$2 crosstab. I found an overall significant difference but I would like to find if there are significant differences among the 4 groups. Is there a way ...
0
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0answers
18 views

column proportions comparisons for one variable

I have a one variable with three categories like marriage/divorced/widowed. The counts are: 40, 23, 7. I use SPSS in this case. I know how to perform chi_squared test for this, and it shows that the ...
0
votes
1answer
26 views

How to compare concentration ratios

I did a spectrometry measurement with the evaluation of the concentration of an element. For the element of interest I've two peaks (with normal distribution). $ C_1 ± \sigma_1 $ where $ \sigma_1 ...
0
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0answers
25 views

Multiple comparisons, multidimensional data, several groups

Could you please help me with such a problem: Let's assume I have multidimensional data that consists of 30 samples and 10 variables. This is a 30x10 matrix. I have three groups of equal size (10 ...
0
votes
0answers
17 views

FDR calculation on non-p-value probabilities

From a meta analysis, I have a distribution of probabilities that are not p-values (i.e., they are not uniformly distributed when H0 is true). I am using these probabilities for an intersection-union ...
0
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0answers
19 views

regression analysis for dataset with few predictors and few samples

I have a small pilot dataset containing experimental measurements for 12 samples, 4 numeric predictors and 1 numeric outcome variable. The goal is to obtain a first rough estimate on the extent to ...
3
votes
2answers
20 views

Multiple comparisons when investigating consistency of a device

I am trying to compare the performance of two devices designed to cool anaesthetised patients. This is a substudy analysis and the patient allocation between the groups is not even. Once cooling was ...
0
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0answers
43 views

Correcting for multiple testing on non-independent sliding windows

Question Values taken from adjecent windows in a sliding windows are corrolated. If I calculate a p-value from each window, how can I correct for the fact I have tested many windows, given that the ...
1
vote
1answer
24 views

Distribution comparison across different treatments

if I have a table like this In which, site = different sites of measurement (tissue or organ) type = different types of virus And I want to ask something about the data 1.What test can I use to ...
4
votes
1answer
45 views

What is the intuition for dependence assumption in Benjamini and Hochberg (1995)?

For dealing with multiple testing, Benjamini and Hochberg (1995) assume that the tests are independent. Benjamini and Yekutieli (2001) show that (1) the 1995 result also holds under (I think) weaker ...
1
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0answers
32 views

Multiple comparisons on nested subsets of data for a non-parametric test

My problem: I'm using data sets where some are nested in a non-parametric test that expects independent data sets. How can I correct for that in a way that is reasonable? Or even better: What would ...
2
votes
1answer
37 views

Difference in difference model with 2 treatment groups

I have an experiment which has 2 treatment groups(effects) and a control group. Up until this point in my analysis, I've been carrying out a DID using a regression equation of the form: Y= γD_t + ...
1
vote
0answers
73 views

MHT: Pre-Selecting statistical tests without Bias

Summary: The last formula boxed in red (which is a modified log likelihood from logistic regression) is a special non-differentiable loss function that is adapted to contain a Bonferroni correction in ...
6
votes
2answers
155 views

The meaning of “positive dependency” as a condition to use the usual method for FDR control

Benjamini and Hochberg developed the first (and still most widely used, I think) method for controlling the false discovery rate (FDR). I want to start with a bunch of P values, each for a different ...
5
votes
2answers
101 views

Why am I getting a 10-15% type I error rate for a 2 x 2 ANOVA?

While testing type I error rate using R, I found that I am getting higher than 5% false positives with a 2-way ANOVA. However, I thought one of the reasons for using an ANOVA (as opposed to multiple ...
1
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0answers
23 views

How to adjust for multiple comparisons with a large number of ANOVAs?

I have a complex experimental design: 3 groups, each of which come on 4 occassions and I obtain recordings from 250 skin electrodes. I am interested in knowing which of the electrodes provides a ...
2
votes
2answers
46 views

Multiple comparisons with t-test: one group with different variance

If I have 3 groups that I want to compare with a t-test (correcting for multiple comparisons afterwards) but one of the groups has different variance than the other two, should I use a Welch ...