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Questions tagged [centering]

Centering involves subtracting the overall sample mean score from the original score; standardizing does the same followed by dividing by the overall sample standard deviation.

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p-values change after mean centering with interaction terms. How to test for significance?

I assumed the following interaction model: $$y = \beta_0 + \beta_1 x_1 + \beta_2 x_2 + \beta_3 x_3 + \beta_4 x_2 x_3$$ And then applied mean centering: $$y = \beta_0 + \beta_1(x_1 - \bar{x_1}) + \...
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Mean-centering changes the values of regression coefficients with interaction terms [duplicate]

To my knowledge, mean-centering does affect the values of regression coefficient for variables involved with interaction terms. But it does reduce the standard errors of the coefficient estimates for ...
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28 views

How does centering affects the interpretation of the marginal effects?

I am trying to understand how centering continuous variables in a linear regression that includes an interaction term between two continuous variables, affect the interpretation of marginal effects. ...
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19 views

Within-subject centering of a repeatedly measured dichotomous variable in a multilevel model?

I'm currently working on a nested data set consisting of 100 subjects which answered several questions at home on five consecutive days (ecological momentary assessment). Among them, they were asked ...
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32 views

To center or not to center? [duplicate]

I am using a linear regression model to determine the effect of diet score at baseline as predictor of weight at follow up where: lm(weight_followup ~ Diet_Score*weight_base) When I center my ...
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25 views

Should grand-mean centering happen in long or wide dataset?

This seems like a simple question but I've been having a hard time finding an answer. In a long daily diary dataset where each day has a row, the person mean for a given level-1 variable is repeated ...
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15 views

Disaggregating between/within person variance for categorical level 1 variables?

I'm working with daily diary data that include a categorical variable indicating which of 4 possible events happened that day. I dummy-coded this variable and entered it into my multilevel model. ...
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34 views

Mediation and centering

I am running a mediation model with 2 interaction terms (gender x happiness and gender x hours spent working per week) and one dependent term (income). I am wondering if I should mean center these ...
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1answer
199 views

Mean centering interaction terms

I want to mean center my interaction terms in a regression model (i.e., make the mean zero for each variable). I understand that I am supposed to mean center my variables first and then multiply them ...
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33 views

Centering variables in multidimensional data

Assume you have a panel data set, that means for each car (CAR), with several individuals (IDs), the dependent variable is given as the power (POWER) created by an engine, over time (time). Further ...
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1answer
55 views

In linear regression, what would it do to center the label?

In this question linked below, it was addressed why we would center the features in linear regression. When conducting multiple regression, when should you center your predictor variables & when ...
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39 views

Need to center continuous variables in GAMs?

This is just a quick question, but I remember reading somewhere that continuous variables used in splines for generalized additive models ought to be centered (especially for GAMs rather than just as ...
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1answer
32 views

Centering input data for Robust PCA (RPCA)?

I know that before running Principal component analys, the input data needs to be centered around its mean (subtract the mean from each keypoint) before running the algorithm. Do I need to center my ...
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Does centering really help interpret the intercept? [duplicate]

Various people have advocated centering independent variables in regression, on the grounds that the intercept then refers to a sensible point (the mean of each IV) rather than the often impossible ...
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58 views

Within-person centering the outcome variable?

What do you think of within-person centering the outcome variable? If my research questions is clearly about within-person effects (in a longitudinal multilevel model), can I just use the centered ...
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89 views

Centering / standardizing leads to very different results for GLM (logistic, poisson, negative binomial distribution)

I have a dataset with count data and around 1 million observations. My regressions contain around 40 variables (binary and continuous) and 10 thousand fixed effects. I analyze this dataset with linear,...
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95 views

Centering in longitudinal linear mixed modeling - center by participant mean, timepoint mean, or participant by time grand mean?

EDIT: I was incorrectly looking to center my outcome variables. Only center predictors, and decide on group mean or grand mean centering by how you want to interpret your intercept. I have 150 ...
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1answer
113 views

Grand-mean centering in GLMM changes estimates for variance (and everything else)?

I know that when running a linear mixed effects model, centering around the grand mean should change the estimates for the coefficients, but not the estimate for the variance. For example, I have ...
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1answer
45 views

symbol for mean centering

I am struggling to write up an equation in the manuscript of a scientific paper, where two of the terms are mean centered around the group mean. In addition, the mean centering is done with excluding ...
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1answer
310 views

Penalize the intercept in lasso (L1) penalized logistic regression or not?

In logistic regression: $log(\frac{p(x)}{1-p(x)}) = \beta_0 + \beta_1x$, let $x' = \frac{x-\bar{x}}{\sigma_x}$, then in terms of the centered and scaled varaible $x'$ , $$ log(\frac{p(x')}{1-p(x')}) ...
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182 views

How can centering predictor variables reduce correlation between them?

In Statistical Rethinking by Richard McElreath on pg. 320 he states “centering predictors can aid in inference, by reducing correlations among parameters”. For a linear equation with an interaction ...
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1answer
294 views

categorical predictors in partial least squares

I am interested in running a partial least squares analysis using PROC PLS in SAS 9.4. I understand that, by default, the predictors and response variables in PLS are centered to a mean 0 and scaled ...
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60 views

Mean centering and normalization along every dimension or over whole dataset

I'm working a side project which involves using a pre-trained CNN and I came across a piece of code that made me question some of my recently gained knowledge around mean centering and normalization. ...
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1answer
89 views

centering in mixed effect logistic regression

I am working with a mixed-effect logistic regression with two independents (a and b, dummy coded 0 or 1), which have a fixed effect for a, b and the paired interaction as well as a random effect of M ...
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Is it wrong to standardise a variable and then centre it for use in multiple regression? [duplicate]

Is it wrong to standardise a variable (e.g. polygenic risk score) and then centre it for use in multiple regression?
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113 views

Why are the normal equations $X_c(X_c'X_c)^{-1}X_c^Ty$ for centered OLS?

I'm working through a centered OLS problem. If $X$ has an intercept column, $y = X\beta + \epsilon \Rightarrow y = X_c\beta_c + \gamma_0 + \epsilon$ where $X_c$ is the centered design matrix. My ...
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713 views

Multicollinearity and centering [duplicate]

I read nearly all topics about collinearity but still have some questions... I know: multicollinearity is a problem because if two predictors measure approximately the same it is nearly impossible to ...
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149 views

Multinomial logistic regression - centering and using dummy coding?

I have two IV's: cognitive ability test scores (a continuous variable), and task difficulty levels (3 levels: easy, medium, difficult) I want to predict a categorical outcome with 3 types of behavior (...
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1answer
20 views

Rank of N x D vs D x N matrices

If $X$ is a random $N \times D$ matrix where $N > D$, then why is the rank of X - mean(X, 1) $D$ while the rank of ...
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2answers
91 views

choice of mean for mean centering

I am doing statistical analysis of empirical data using a a generalized ordered regression model. I would like to test for interaction terms. I have a 3-level categorical IV (coded as 2 dummy ...
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2answers
94 views

Analyses when IVs highly correlated - is there anything I can do?

I'm doing some analyses in which I have 1 continuous independent variable (IV) and 1 dichotomous independent variable (IV2) that's a demographic covariate. I'm now realizing that they are extremely ...
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1answer
1k views

Why does my centered variable not have zero mean?

It is well established that centering a variable, i.e. subtracting the mean of that variable from every value produces a variable with zero mean. For example: ...
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55 views

Center data in quantile regression?

I have 25 years of nest initiation dates, I used quantile regression to look for changes in the distribution over time, as well as to look in detail to early and late breeders. My model would be ...
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1answer
409 views

Should I use mean centering or not?

I am using a logistic regression model. I want to see interaction effect of a continuous Independent variable on the relationship of another binary independent variable and the dependent variable(DV ...
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26 views

How to represent multiple data by single value

I have three inputs x1,x2,x3 and to each single input there are three outputs y1, y2, y3. (1) x1 --y1, y2, y3 (2) x2 --y1, y2, y3 (3) x3 --y1, y2, y3 The Whole whole set has to be represented by ...
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173 views

Representative terms per clusters based on tf-idf

I have a result of text clustering based on TF-IDF. I have $k$ clusters. How can I get the representative terms for each cluster $I=1,\dots,k$ using the TF-IDF matrix? Is there any standard way to do ...
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1answer
834 views

Decision to center fixed effects in GLMMs in lme4

I'm constructing a GLMM using lme4 in R, and am unsure as to when it is and isn't best practice to center fixed effects. For this model (with logit link), for example: ...
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1answer
41 views

Should I center the data when performing Laplacian Eigenmap or any other manifold learning?

Suppose I have a high dimensional non-stationary non-linear time series, then is it advisable to center the data on the mean when performing laplacian eigenmap? I've heard somewhere that when ...
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Why does the standard error of the intercept change when we shift the axis, say by centering? [duplicate]

I was trying to understand how the calculations are done behind lm() function in R using mtcars dataset. I understand that ...
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55 views

Variable centering on the sampling distribution of the coefficient estimates

I think the question may be silly but I'm trying to learn statistics and R and this is really hard for me because I'm a newbie of both. I have this exercise to do. Carry out a simulation ...
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47 views

What should I to do to cope with multicollinearity problem?

I employed a multiple regression model by applying a backwards selection method of model selection to examine the influence of three explanatory variables their interactions in determining oxygen ...
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60 views

Is there a rule of thumb to choose a specific standardization method for regression?

I have been reading some resources and various techniques have been used to standardize the predictors in a regression model. Below, the first two are common approaches as far as I understand. The ...
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194 views

Formulate a z-test into a general linear model

I've heard it said that most statistical tests can be reformulated within the GLM framework. I can see how that can be done with a two-sample t-test (dummy code group membership and interpret the ...
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1answer
394 views

Scores are still correlated after PCA

I have 22 variables with more than 6000 observations. They are highly correlated. I know these data would work as great explanatory variables to a dichotomous event (present absent). Therefore, I ...
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226 views

Centering and assumptions of 3-level multilevel model

I am struggling with formulating a multilevel model for my analysis and would really appreciate if you could give me some insight. This is a 3-level model where the response (Y), exposure (X), and ...
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1answer
814 views

Standard deviation non centered (normal) data

I'd like to get a prediction interval (or a good measure of dispersion) of my data but it seems like standard deviation is not the right way to do it because my data is not centered (or not normally ...
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1answer
1k views

Mean centering or not in the context of Partial Least Squares

In my current project, I'm using PLS regression on infrared spectra (FTIR). For this I'm using R and the pls function from the plsr package. ...
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Does random forest need input variables to be scaled or centered?

My input variables have different dimensions. Some variables are decimal while some are hundreds. Is it essential to center (subtract mean) or scale (divide by standard deviation) these input ...
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1answer
746 views

How to conduct meta-regression with continuous and categorial variables?

I am conducting a meta-analysis in psychotherapy research and want to use meta-regression to identify moderators. The regression outcome is a correlation between a psychotherapy process variable + ...
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691 views

What are the advantages of the pre-defined initial centroids in clustering ?

In many clustering techniques, the values of initial centroids (center) play an important role to draw the results of the clustering process. Could someone please tell me what are exactly the ...