Questions tagged [adjustment]

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2
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1answer
54 views

Is there any consensus on adjusting p-values for multiple tests?

I'm confused as to when adjustments for multiple tests need to be used. I'm an undergrad who's familiarising himself with stats, so apologies if my question sounds dumb, but I haven't found any ...
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0answers
13 views

Paired comparison of multiple variables, how/whether to adjust for multiplicity

I would like to ask for advice about which statistical test to use. I want to compare the control left and the treated right knees of the same 10 patients (n=10 per group, paired comparison). I did ...
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1answer
16 views

Multiplicity correction when using emtrends to see if slopes are different from 0

I have a relatively straightforward question but I haven't been able to find the answer. Consider this example: ...
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0answers
25 views

Can controlling for baseline in a regression with change scores be appropriate? (within-subjects design)

I ran a regression model with a change score (post minus pre manipulation) predicting my dependent variable. Initially, I thought it might be also interesting to control for the baseline score (pre ...
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0answers
8 views

When do I have to correct for multiple comparison when computing different mutiple regression models?

I' ve got a problem with my thesis. I use a set of 3 bloodbiomarkers plus age as a covariate to predict Marker of Functional Connectivity on the one hand and Structural Connectivity on the other hand. ...
4
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1answer
45 views

Why match if you have the control data already?

I had a question about matching. I understand the benefits of matching prior to conducting a study due to potential increases in statistical efficiency/ adjustment for confounders. Let's say you're ...
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12 views

Phenotypes adjusted by Fixed effects - How to adjust a Covariate - R

Using as an example this file: ...
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0answers
19 views

Adjust cumulative incidence function curve by multiple variables in competing risks?

I am calculating a Fine & Gray Model for a data set with competing risks present. I got all the coefficients and their p-values. I know it's possible to plot estimated cumulative incidence curves ...
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0answers
21 views

Population-adjustment for Poisson regression

I am a novice to R but am trying to use it for my project, where I am using census tract level data with different population counts to create a regression model that calculates the association ...
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0answers
10 views

Interpretation of Adjusted Predictions Contrasts (Margins)

I would really appreciate some help with interpreting results for contrasts of adjusted predictions (I use Stata 15, margins command). I run an experiment and fitted a regression model comparing the ...
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0answers
14 views

Question regarding p-value adjustment for multiple comparison across multiple experiment

This is my first question and it's about p-value adjustment for multiple comparison in the setting we conducted multiple experiments. We performed several viral infection experiment in specified ...
0
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1answer
31 views

Comment on the change in p-value following adjustment for confounders

The Second Australian National Blood Pressure Study (ANBP2) was a prospective, randomised, open-labelled, blinded to endpoint (PROBE) trial of Angiotensin Converting Enzyme (ACE) inhibitors versus ...
2
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2answers
50 views

Adjust alpha when switching from one-tailed t-test to two-tailed

I started with a hypothesis that says e.g. A is larger than B which would usually call for a one-tailed t-test. But after acquiring the data it turns out that the effect seems to be contrary to my ...
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1answer
79 views

Matthews/Phi Coefficient on a 2x2 Contingency Table with Rare Positives

Suppose I want to measure the degree people like gold versus silver. For the sake of argument, let's say I have a contingency table like so: ...
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1answer
46 views

Do I need to correct for p-value when doing repeated ANOVA test?

We are investigating the relationship between smoking status and the hormone level. Smoking status is X(three-level) and the level of the hormones is Y(continuous variable). However, the smoking ...
1
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1answer
31 views

How to adjust a confounder in pre-post analyis

I have a paired-dataset of pre and post-surgery measurements of certain biomarkers. I have done a paired t-test to find if there is a difference in the levels of a biomarker, say x1, before and after ...
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1answer
16 views

Unadjusted rates vs. observed rates?

In poisson and negative binomial rate models, should the observed rate be the same as the unadjusted rate (in model with only 1 variable)? Should you report these unadjusted rates from a model with ...
2
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0answers
29 views

'hold constant' and 'adjust for', do these terms have the same meaning?

In the context of regression, is there a difference between saying you held x constant and saying you adjusted for x? Or are these exactly the same thing? Thank you!
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18 views

Moderation vs adjustment in statistics

Can anyone tell me what is the difference between moderation and adjustment in statistics? And who to conduct each of them in regression analysis using SPSS? I would appreciate any help.
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32 views

How to adjust P values for several Post Hoc tests

I have several continuous dependent variables x1,x2,x3, and one categorical independent variable x4 with 4 levels, I want to apply ANOVA for each of these dependent variables one by one and then do ...
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1answer
29 views

Ideal method for confounder adjustment

I have a fairly large dataset (15,000) in which I assessed the association of a three-level categorical risk factor to the outcome. The outcomes were significantly different for the three levels. ...
2
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1answer
222 views

Multiple minimally sufficient adjustment sets in a Directed Acyclic Graph (DAG): Which unbiased estimate should be presented?

Assume that you want to estimate the effect of $X$ (exposure) on $Y$ (outcome). A common question is: What variables should we adjust for in our model in order to get an unbiased estimate of the ...
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0answers
23 views

Data normalization (reward/penalization) in a learning paradigm

wondering if folks can offer guidance on this data normalization problem. When trying to determine retention of information after a time delay, the retention rate needs to be adjusted for # of items ...
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0answers
58 views

how to perform Discrete Bonferoni- Holm adjustment to multiple p values

For my thesis, I'm performing a CochransQ test after which I want to use exact Mcnemar tests to illustrate where the differences are between 6 different methods with binomial responses. I found this ...
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0answers
28 views

Need of p-value adjustment when analyzing all possible pairs of factor levels in linear model

I have a nominal (not ordinal) variable with $K$ levels (these are actualy some groups of patients) and I run linear model in which: this nominal variable is one of IV's (others are age, sex and so ...
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0answers
6 views

Strong covariates and weak biological signal in transcriptomes

My experiment aims to test the interaction between heterologous genes in a double transgenic mouse model. Basically the interaction of viral genes with 3 different variants of a human gene. The gene ...
1
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1answer
52 views

Using binary outcome variables in real-world data studies must be wrong?

Please be gentle if it's a stupid(ly easy) question: In medical literature lot's of randomised clinical trials use binary outcome variables, such as 90% reduction in Y, or Y<(a certain threshold). ...
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1answer
20 views

Known Correlation between predictors

I have two predictors and an outcome, let's call them x, y and z. I know that x and y are correlated with correlation r. I am trying to construct a linear model: z = ax + by + c I have an ...
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0answers
25 views

Highly significant t-test statistics, any way to correct this?

I have been performing several paired t-test, where I test whether the sample means are different between two groups. For all of my tests (approx. 30), which all carries 13-14,000 observations, I ...
4
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2answers
364 views

Should all adjustments be random effects in a mixed linear effect?

I've been sometimes taught that when you are performing a mixed model, any variable of which you don't care about estimating a parameter (adjusment variable) should be a random effect, regardless of ...
1
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1answer
209 views

Significance of correlation with range restriction in x

Background Range restriction can happen in various study designs and it affects the results of bivariate correlation or in multiple regression, for example. In some cases the range restriction may be ...
0
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1answer
64 views

Deriving the values of the range around the mean value

This is part of a bigger quantitative reasoning assignment I was working on. My understanding here is that the upper bound and lower bound of the ranges for each of the exercises should be reflected ...
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2answers
446 views

How to calculate Mean adjusted by Covariate?

I need to calculate the mean of a variable, adjusted by another variable. Both variables are ratio scaled. I found this online: https://ideas.repec.org/c/boc/bocode/s344803.html which does what I want,...
2
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1answer
122 views

Adjust ROC analysis for multiple testing?

we did an exploratory prospective study in medicine in order to find parameters which are able to predict a specific post-surgical event (0/1) before the actual surgery. We have about 10 parameters ...
1
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1answer
272 views

How to do a survival curve adjusted to age in SPSS? [closed]

I have to do a survival curve comparing 3 diseases. Already did a Kaplan Meier since time of diagnosis, and the log rank was p-0.001; however I suspect that it has to do with age (one disease is ...
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0answers
24 views

Adjust two coordinates based on the distance between them [closed]

I have two positions $\overline{X_1} \in \mathbb{R}^{2}$, $\overline{X_2}\in \mathbb{R}^{2}$ with the respectively measurement errors $\Sigma_{X_1}\in \mathbb{R}^{2\times 2}$ and $\Sigma_{X_2} \in \...
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1answer
29 views

Is this a valid method to adjust for multiple testing?

Assuming I have 100 variables and I do a t-test for each of them without adjusting the p-values, and get 8 significant p-values out of the 100 tests. If my alpha is 5% can I just say that since I ...
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0answers
116 views

Statistical adjustment for regression

I already checked out the answer to this: enter link description here It is not a duplicate and that did not answer my question. I wanted to try to ask a different question regarding a similar ...
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0answers
28 views

P value adjustments when subsetting dataframe

I'm analysing a dataset that contains different species. I first use the species ID as an independent variable but then I have to analyse the dataset separated for the different species (in total 3). ...
2
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0answers
167 views

Adjust intraclass correlation for measurement error

It's been known since Spearman (1904) that one can adjust an observed Pearson correlation for measurement error using this formula (R code with tidyverse attached): ...
6
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2answers
128 views

Significance testing when the treatment group was only partially treated (an unknown set of individuals did not receive the treatment)

I have a somewhat messy experiment that has already been conducted with large test and control groups, and have measured the response variables (sales / individual, etc). A known percentage of the '...
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0answers
30 views

Adjusting the values of the dependent variables after running a regression model

I have data coming from a satisfaction survey that was done in a big global company. In this survey, the managers of the different departments were rated by their employees (satisfaction from the ...
12
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1answer
415 views

Is meta-analysis of odds ratios essentially hopeless?

In a recent paper Norton et al. (2018)$^{[1]}$ state that Different odds ratios from the same study cannot be compared when the statistical models that result in odds ratio estimates have ...
0
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1answer
46 views

Adjusting Nutrient Intake for Energy Intake OR Body Weight OR Both?

Introduction I am analyzing a data set which I am grouping in protein intake quartiles. Before using the protein intake data (in grams), I want to adjust it to avoid potential confounding. Problem ...
2
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1answer
28 views

Multiple hypothesis test

I have some questions about multiple hypothesis test. Situation 1: We have 1000 p-values, all of them are less than 0.0 5. We may say there are 50 false positive (1000*0.05) in these p-values. ...
0
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1answer
535 views

Matching by or adjusting for confounders?

When using regression models with a binary exposure, how do you choose whether to adjust for a confounders as covariates or to match the two exposure groups according to the confounders and then ...
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0answers
215 views

adjusted p-values for post-hoc tests?

I'm analysing about 20 lab-results of three different groups either with ANOVA, Kruskal–Wallis test or chi-squared. I correct the resulting p-values for multiple testing using the Benjamini/Hochberg ...
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0answers
40 views

Adjusting simultaneously for multiple confounders

I am having trouble understanding how to adjust for confounders in a basic statistical analysis. As a simple example, assume I want to know whether the weight of group of sick subjects and a group of ...
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0answers
109 views

Should the Kaplan-Meier p-value be adjusted if new data are added?

The event of interest is subscription purchase and the time variable is days since the creation of the subscription trial within an AB Test. The stakeholders want to monitor the progress each day as ...
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0answers
56 views

Correlation with adjustment

I have data from several animals that are tested daily for 15 days on the presence of seizures. I have the latency of the seizures(when it begins after the start of experiment) and they occur on some ...