Stack Exchange Network

Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

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.

1
vote
1answer
17 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 ...
2
votes
1answer
15 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 ...
1
vote
0answers
30 views

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 ...
1
vote
0answers
17 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 ...
0
votes
0answers
36 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,...
4
votes
1answer
53 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 ...
1
vote
1answer
71 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 ...
2
votes
1answer
34 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 ...
0
votes
1answer
162 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')}) ...
3
votes
1answer
100 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 ...
0
votes
1answer
178 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 ...
0
votes
0answers
39 views

Mean centering fails to make the y-intercept the mean of the dependent variable

To my understanding, after mean centering the independent variable in a simple regression, the y-intercept should equal the mean of the dependent variable. However, after centering in my own dataset ...
1
vote
0answers
37 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. ...
1
vote
1answer
61 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 ...
0
votes
0answers
23 views

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?
0
votes
1answer
97 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 ...
1
vote
0answers
415 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 ...
0
votes
0answers
113 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 (...
0
votes
1answer
19 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 ...
1
vote
2answers
79 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 ...
2
votes
2answers
84 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 ...
3
votes
1answer
942 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: ...
1
vote
0answers
44 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 ...
0
votes
1answer
240 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 ...
-1
votes
1answer
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 ...
2
votes
0answers
163 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 ...
0
votes
1answer
596 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: ...
1
vote
1answer
35 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 ...
1
vote
0answers
36 views

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 ...
1
vote
0answers
52 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 ...
0
votes
0answers
147 views

Standard error of intercept term in centered (standardized) model

When centering or mean-zero standardizing independent variables in a multiple linear regression analysis, it works out that $s.e.(\beta_0)= \sqrt{\sigma^2(\beta_0)}$ of the first diagonal element of $\...
0
votes
0answers
45 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 ...
0
votes
0answers
58 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 ...
0
votes
0answers
138 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 ...
5
votes
1answer
307 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 ...
2
votes
0answers
192 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 ...
0
votes
1answer
628 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 ...
6
votes
1answer
912 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. ...
11
votes
1answer
6k views

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 ...
3
votes
1answer
671 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 + ...
0
votes
2answers
534 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 ...
1
vote
1answer
55 views

Making coefficient for centered binary variable meaningful?

I'm having a hard time making a centered binary variable in a multilevel model interpretable. Here is what I'm working with: at Level 1, I have a binary variable indicating whether a participant gets ...
2
votes
0answers
459 views

Interpreting centered binary variable in MLM

I'm using multilevel modeling in a situation where I must center a level 1 binary predictor (coded 0/1), following recommendations made here: https://www.researchgate.net/profile/Davood_Tofighi/...
1
vote
0answers
359 views

Should dummy variables be normalized along with numeric variables when doing kmeans clustering

I am trying to cluster the data set 'How Americans spend their time' using kmeans clustering. The data set contains education, gender and age-range (55-60, 60-65 etc) as categorical variables and ...
1
vote
0answers
240 views

Person- vs. grand-mean centering in Mixed Effects Model

I have a data set containing data of roughly 300 individuals with for each individual at most 3 observations. I want to make a simple mixed effects model of the form ...
1
vote
0answers
613 views

Implications of group mean centering predictors in unbalanced, multi-level modelling

As we all know, centering predictor variables is an important topic in statistical inference, and can severely influence interpretations of parameters for lay audiences. In multilevel models, ...
2
votes
1answer
159 views

How to interpret whether centering improves linear regression model or not?

I'm doing my first tests with linear regression and centering and on the linear regression model with dichotomic predictor that I have, I'm wondering how to interpret whether centering improves the ...
1
vote
0answers
60 views

Applying PC rotation obtained from centered data to un-centered data

Let $X$ be an $n\times p$ matrix. We obtain a matrix $Z$ by removing the mean from each column of $X$. Let $Z=UDV^T$. Principal components are $Z \cdot V$. What is the interpretation of $X \cdot V$?
0
votes
1answer
85 views

Making the linear and quadratic terms independent in temporal data

I'm looking at the abundance of different groups of humans over time. These abundance data closely follow a quadratic model of the form $y=a_{0}+a_{1}x+a_{2}x^{2}+ \varepsilon$ for all groups of ...
3
votes
0answers
529 views

R: Quadratic Regression with interaction: when to center?

I have a statistical question. I have data from an experiment with two conditions (dichotomous IV: 'condition'). I also want to make use of another IV which is metric ('hh'). My DV is also metric ('...