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Questions tagged [adjustment]

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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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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 ...
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2answers
301 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 ...
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1answer
86 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 ...
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1answer
19 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
47 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,...
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1answer
37 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 ...
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38 views

How to do a survival curve adjusted to age in SPSS?

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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23 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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17 views

Poisson bias adjustment

So I was hoping someone could help me make sense of this problem. I came across this paper that discusses how the FSL probabilistic DTT may yield bias tractography relating to the physical distances ...
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1answer
26 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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Log-linear BIAS adjustment

I have a loglinear model of: $log(\mu(S_{ij|gij}))=\alpha_0+\alpha_1g_{ij}$ where gij is distance, and Sij is connectivity There is a bias in the distribution of count values for the outcome ...
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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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17 views

Calculation of adjusted CDS spread changes in event study

I am conducting a study about the impact of credit ratings on credit default swap spreads for European Sovereigns. In the related literature, most authors use adjusted spread changes to account for ...
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27 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). ...
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116 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): ...
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60 views

Significance Testing with Known Control-like Contamination in Test Group

Spent a lot of time searching and haven't found an answer - apologies if this was asked before worded differently. I have a somewhat messy experiment that has already been conducted with large test ...
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27 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 ...
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1answer
270 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 ...
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313 views

P-value adjustment for hierarchical / multilevel data

I'm dealing with a large data set which is hierarchical in nature, that is 1000 schools, within every school 1000 students. The dependent variable is a measure of performance. Ideally I would like to ...
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1answer
28 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 ...
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1answer
25 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. ...
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26 views

Adjusting dependent variable using regression

I have seen multiple posts and studies which used fitted values from regression to get co-variate adjusted dependent variable. Here are some to name a few: 1, 2 and 3. But I don't quite understand ...
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Adjusting for energy intake (one sample)

I have a data set with percentage of energy intake from fruits at the baseline and after 2-years (one sample only). 1) When I am making a regression analysis on this change and its effect on body ...
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1answer
107 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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111 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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15 views

Method to adjust probability of an outcome for number at risk

Sorry if this is a silly question. I have a table of 2000 patients and the time at which a certain in-hospital outcome occurred. I have another table of these 2000 patients containing how long they ...
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26 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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76 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
43 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 ...
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1answer
703 views

How to detect seasonality in data in R?

My goal is to (1) prove the hypothesis of seasonality in this inflation time-series and (2) remove the seasonality via the X-13-ARIMA-SEATS procedure. My questions are (1) how does one prove such ...
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0answers
16 views

Adjusting/controlling entire distribution for covariates

Suppose I have data on the number of views that Youtube music videos receive as of a fixed date. Let $Y_i$ represent the number of views that video $i$ has received by this date. I want to compare the ...
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3answers
137 views

Bonfferroni correction of correlation p-values. What's my k?

I ran a series of Pearson correlations on my data and my supervisor told me to correct the p-values to account for the multiple comparisons I made. She told me to divide the p-value by the number of ...
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42 views

After making an adjustment to the forecast, should I also adjust the prediction interval (& how)?

I want this to be a general question as it may help others in the future but I will give the specifics of what I'm doing. I am producing forecasts for many time series with different models. It is ...
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217 views

How to report multivariate linear regression results

I want to evaluate association between two continuous variables. But in my data, there are confounding factors such as age, weight,... I think that simple correlation analysis is not correct for this ...
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31 views

Do I need to “correct”?

I am testing whether a certain learning intervention affects student achievement. I have two groups of students (control and experimental) with 16 students each. I have their pre-test and post-test ...
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238 views

Adjusting P-Values of one-tailed tests

I am running a large number of two-sample Wilcox tests and using Benjamini, Hochberg, and Yekutieli method to adjust the p-values. The issue is that when I conduct a one-tailed test, the p-values ...
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2answers
2k views

Can I calculate adjusted means from ANCOVA if data is unbalanced?

I have a 10k lines dataframes on which I want to perform ANCOVA so I can get adjusted means. Please note that I've never done this before so I jump from a tutorial to another, but I still want to ...
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1answer
66 views

Does the Mann-Whitney U-test need to be adjusted in twin studies?

I have data from 44 twin pairs (88 patients total) and they are split into group_A (n=50) and group_B (n=38). For each of the ...
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132 views

How to adjust for confounding variables across different study periods?

I have a continuous & categorical outcome variables in three groups of patients, where the groups are defined by time periods 2010-2011, 2012-2014, 2015-2016. I found out that age and gender are ...
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1answer
183 views

Re-weight a data to match summary statistics of another dataset

I am trying to conduct a matching-adjusted indirect comparison (MAIC) using R. The process is similar to propensity score weighting. The process involves reweighting subjects in a population so that ...
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3answers
198 views

Age-adjustment (and its realization with mgcv): add age as covariate to the regression or do an internal standardization?

This question consists of two - but possibly related - parts. Question #1 We have data on the occurrence of a disease in several age groups over several years. We try to investigate the secular ...
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1answer
107 views

How can I adjust values in a timeseries to account for effects from other variable(s)? i.e. using a GAM

I have a dataset of monthly air pollution levels (i.e. PM2.5) as well as a corresponding dataset with monthly rainfall amount (i.e mm) spanning several years. These datasets have moderately strong, ...
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1answer
34 views

Correcting temperature data for seasonality given the outside air temp

I'm wondering how I could use historical outside air temperature to correct/adjust temp sensor readings I have. I know how to adjust for seasonality in accounting/forecasting where I would use my ...
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1answer
24 views

Unmeasured covariate adjustment

A study was presented where the authors used multivariable logistic regression to assess association between a risk factor and an incident disease outcome. The association was statistically ...
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1answer
166 views

Adjusting variable for covariate to calculate rates or metric

In this report by Dartmouth Institute, rates of utilisation (per patient) were reported by year and regions. The input measure of utilisation were said to have been adjusted for differences in age, ...
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2answers
430 views

How to test a covariate adjustment for propensity score matching?

How can I test whether a covariate is sufficiently balanced after propensity score matching is made? Some authors say that standardized difference less than 0.1 is enough. Some authors say that ...
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0answers
56 views

Adjusting OR for confounding variable with non linear interaction

I have looked for similar cases but couldn't really find the answer to my question. I want to assess the impact (with an OR in logistic regression) of a predictor X1 on a binary response variable Y ...
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0answers
21 views

Mix Design: Failure to predict response

I have performed a mixture design containing 3 terms and I have carried out 6 experiments needed to adjust a quadratic model. It fitted the data quite well: ...
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1answer
63 views

Adjust for one factor in time series analysis

I would like to analyze whether blood pressure is higher in winter than in summer through time series analysis: in particular, I would like to use repeated/pooled cross-sectional time series analysis ...