# 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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### Centering predictors in linear mixed effects and explaining three-way interactions with continuous variables [duplicate]

I am working on a Linear Mixed Effects model. All four predictors are continuous variables. Full model: ...
• 35
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### Centering in 2 level Multilevel modeling

When two level-1 variables interact with each other, some articles recommend using cluster mean centering, rather than the grand mean centering. However, I do not understand why I should not use grand ...
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### centering issue in the multilevel modeling

I learned that categorical variable should be centered just like continuous variable. I am analyzing two level model, (MLM). case 1. when the categorical variable is level 1 predictor, and have ...
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### Subject-specific predictor centering based on observed value of dependent variable

In a study on human movement mechanics, my variables are 1) an indicator of performance, and 2) a vector describing one's average body configuration. Hundreds of observations are recorded for each ...
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### Mahalanobis vs centering / standard deviations

Is there a difference whether to use a Mahalanobis distance or transform the data via centering (and normalization) when you are interested in calculating distances? This means, if you are interested ...
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### Understanding centralization and normalization

I have the following task where I am given an audio signal: Center the signal (subtract the mean value) and normalize to a dynamic range of -1 to 1 (divide be maximum of the absolute value). If I ...
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### Should I center and standarize in a PCA of relative growth?

Im quite familiar with PCA, but as a non-pure-statician I have come here to ask for help and comments. I have a dataset with multiple meassures (End and initial for a lot of meassures), and the time ...
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### What does it mean if we use eigenvetor matrix of centered matrix $\mathbf{X}$ to reduce the dimension of $\mathbf{X}$ without centering?

Recently, I was trying to use PCA to reduce the dimension of matrix $\mathbf{X}$. Suppose a data matrix $\mathbf{X}\in \mathbb{C}^{M\times N}$, where $M$ is the number of variables and $N$ is the ...
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### "Group mean centering" a dummy Variable in R for multilevel analysis: how can i do this?

have somebody an idea of how to group mean center a dummy Level 1 predictor in R? Enders & Tofighi (2007) describe a method to center a dummy variable through substracting the proportion of the ...
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### PCA whitening and centering in inference/test samples

[cross-posted from SO] I'm working on speaker identification. I need to take the speaker embeddings from a neural network and apply a few transformations to finally generate the score for verification....
65 views

### Centering the Mediator in Multilevel Mediation

I want to run a parallel mediation analysis with lavaan. My data is nested, so I implement two levels. The mediation is on one level (1-1-1). Because of the nested data, I want to use the group-mean-...
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### How does group mean centering affect the interpretation of coefficients in a hierarchical model?

I've dived deeply into the literature, but still don't understand if it's necessary to group-mean center my predictors if I'm entering them into a hierarchical model. Surely, if they're being entered ...
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### original mean from centered array

Given the mean-centered array a <- c(-2.25,0.75,-1.25,2.75,-0.25,1.75,-0.25,-1.25) is it possible to retrieve the mean of the original array used to center it ...
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### center continuous predictor such that intercept represents first value of predictor

Maybe a stupid question, but I would like to center a continuous predictor (having 3 levels) so that the intercept in my linear mixed effects model represents the first value of my continuous ...
1 vote
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### When is ok not to centre the data before using it in PCA?

I want to find out if it is ok not to center the data in a PCA when working with stock returns. Centering would remove the trend from the dataset which I believe contains valuable information. The ...
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### Multiple regression variable centering when model building, to model input variables or both?

I am working with GLS linear models. I have a transformed dependent variable (log) and 2-3 independent variables. Now I am aware of the basic ideas surround scaling and/or centering variables. I am ...
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### Can I GROUPMEAN center one variable and not the second one involved in an interaction / Multilevel Model with L1 Moderation

I'm fitting a multilevel model with an L1 moderation on Mplus. I am trying to demonstrate that the effect of X (independent variable / mean of scale items) on Y holds only when people do not make a ...
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1 vote
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### Cosine similarity with recentering - collaborative filtering

I don’t know much about stats (nor maths), so I’m sorry if I’m not being very clear on this... I’m trying to build a simple recommender system for books using collaborative filtering item by item. I’...
1 vote
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### Problems with 0s when centering a dummy variable within cluster

Supposing that I have a set of data that is structured like this: customerID orderID couponUse purchaseQuantity 1 1a 1 3 1 1b 0 1 1 1c 0 1 2 2a 1 5 2 2b 1 2 3 3a 1 6 3 3b 1 3 3 3c 1 7 3 3d 1 ...
1 vote
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### Centring in three levels multilevel models with cross-level interaction

I am relatively new to multi-level models subject and find it challenging to connect theory to modelling. My interest is to examine the moderation influence of green space (at level 3) on the ...
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1 vote
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### Linear Mixed Effects - degenerate Hessian with 1 negative eigenvalue

I am using linear mixed effects to look at how the variable Neuro (measured at baseline only) predicts change over time in the variable Score (measured at baseline, visit 2 and for some participants ...
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### Group centering for interactions with within-between mixed panel model

I need to update a model to incorporate an interaction between a time-invariant categorical variable and a demeaned time-variant variable. I'm unsure about how to correctly use group-mean centering ...
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### Why does centering variable A influence my p values of factor B in the linear mixed effects model?

I have a dataset, where I would like to see whether there is a group difference in the measurement "concentration". I have repeated measurements for some subjects, which is why I use a mixed-...
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1 vote
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### Whats the motivation to demean variables when estimating an interaction effect? [duplicate]

I am trying to estimate a regression model where I am interested in the effect of a certain magnitude, probability and expected value (probability * magnitude ) on reaction times. I was told that it ...
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### Mean-centering variables in glmer

I have the following model in r that compares the differences between dives where whales fed and dives where whales didn't fed (distribution is binomial: presence of feeding (foraging) = 1, abscence = ...
1 vote
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### Why does centering NOT cure multicollinearity?

In several posts, such as Is centering a valid solution for multicollinearity?, it states that centering doesn't solve multicollinearity because "it's a linear transformation." I just made ...
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### Applying de-standardised ridge regression coefficients to new test data - how to best handle the mean of y_test?

this is my first post on Stackexchange, so please correct me in any way if I am doing it wrongly. I just stumbled across this question, I was battling with the same issue, but the posts there ...
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1 vote
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### Interpreting repeated-measures oneway ANCOVA

I have a question on how to run a repeated-measures oneway ANCOVA. I have only one within-subjects factor (time) and I am interested in how a construct changes from T1 to T2. I would also like to add ...
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### Should we center a Season Variable for regression?

Suppose that we have the following model $Y = b_{0}+b_{1}*Season +b_{2}*Income$ In order for $b_{0}$ to refer to the expected value of $Y$, we should center the variables Season and Income. However,...
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### Do I use the mean vector from my training set to center my testing set when dimension reducing for classification?

Please let me know if this is the right place to ask this (or if any of my tags are wrong) or if I need to write this any differently. Do I use the mean vector from my training set to center my ...
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### How to center level-2 variables in unbalanced two-level models?

Let's say I have a sample of 200 students and they are clustered in 10 different classrooms. However, the sample is unbalanced such that some schools have more than 20 students and others have fewer ...
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