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Questions tagged [controlling-for-a-variable]

A control variable is one which is included in a model primarily for its impact on the total model rather than for its own substantive interest.

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When to include covariates when I hypothesize there's a difference between groups?

If I am hypothesizing that there is gender difference in a certain domain, and that another variable would moderate the gender difference, should I include covariates in the analysis? The key of this ...
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Compare variable across two groups conditionally on a variable that has a strong correlation with the variable

I have the following scatter plot. I want to do a statistical test to asses something along the following lines: "are the red dots on average higher/lower, given the y-coordinate". But I don't really ...
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Controlling for a variable in OLS - Stratification and Reaggregation. Simple Example

In his engrossing book "Naked Statistics" Charles Wheelan begins to explain how controlling for variables works by stratifying the sample. However, he stops short of explaining the reaggregation, ...
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Regressing out of the *independent* variable?

Using some software packages it is possible to 'regress out confounding variables from the independent variable x' before plotting ...
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How to remove the effect of one variable by using linear model residuals

My data set has species with a number of morphological variables, including body mass: ...
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How to use 5-year ACS census data in an annual regression

Lets say I am running a regression on annual data at the county level and I would like to include some controls based on census data. Some of my counties of interest are below 65k population, so ACS ...
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72 views

Interest rate control variable GARCH

I'm building a GARCH model which looks if analysts' reports affect the volatility of certain stocks. I was wondering if it would be logical to include the interest rate in my GARCH model as a sort of ...
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moderators, control variables and time-fixed effects for panel data using plm package

I have panel data that consists of 33 companies, 70 CEOs and 30 years. I want to measure the effects CEO narcissism (=x) has on the internationalization (= y) of companies. the fixed effects model is ...
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“controlling for” a variable [duplicate]

In my analysis section where I used a partial least squares (PLS) structural equation technique, A reviewer commented that: "Not controlling for state or university etc, particularly in a diverse ...
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Statistical Control vs. Sample Representativeness

Assume I have a sample that is NOT representative of the population. To illustrate an example, assume I the dependent variable called Violations that measures the number of job violations, and I ...
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2answers
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Main effect not significant, but confound is

I am a little bit stuck with my data analysis. What does it mean if your main effect is not significant (.442) but becomes even less significant when you add your control variable (.718) Furthermore,...
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1answer
34 views

Control for variables: multiple regression vs residuals

I'm trying to understand how to control for variables in linear regression. Say I want to predict $\mathrm{outcome}$ using $x_1$ and control for $x_2$ and $x_3$. The common approach I see is just ...
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Controlling for difficulty by weighting

I want to conduct a mixed model Anova. Essentially participants had to count the right amount of zeros from tables containing randomly generated tables of zeros and ones. Performance was measured by ...
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Environmental consequences of FDI and the effect of controlling for GDP growth

I want to estimate the environmental consequences of foreign direct investments on the growth of emissions in a country. Thus, I regress growth in emissions on yearly FDI inflows. I expect this ...
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86 views

Can an uninformative control variable become useful?

I run a multiple regression with an IV that could not explain any variance in the DV. Is it possible that if I add another variable in the model as a control that the IV entered first would start to ...
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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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1answer
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Partial Correlation vs. Interaction

Analysis type: linear mixed-effects model DV: cortisol (4 time points per participant - morning, noon, 5pm, 9pm) IV 1: time-since-waking (continuous, repeated measure, variably spaced/unstructured ...
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Partial correlation with continuous and categorical variables (SPSS)

I have results of 7 neuropsychological tests, and I am studying the convergent/divergent validity of one of these tests. These are the continuous variables. I also have background variables: gender ...
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Controlling for a time point in the DV

I am running a linear mixed model with 5 cortisol time points. I am trying to determine the effect of prior-day bedtime cortisol levels on next-day cortisol slope. I am testing this with an ...
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Discriminant validity between traits that co-vary?

I'm hoping to do a validation study on a measure of anxiety (called the AISCs) in a stroke population, using convergent and divergent validity. A test demonstrates convergent validity if it ...
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1answer
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When we compare groups on control variables should we be using tests of equivalence?

In many papers that consider treatments and outcomes, I see tables (usually "table 1") of what might be called nuisance variables (often demographics, sometimes medical conditions) with tests of ...
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Replacing a control variable by a summary of the dependent variable

I am trying to model the number of (web) page-visits that different products receive during a period of time, using different characteristics of these products. I am using a linear regression model: $...
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2answers
361 views

How does statistical control work in logistic regression?

I want to make sure that I can generally interpret model findings accurately. Is it fair to say that each log-odds associated with a predictor assumes that the others are held constant at 0? Making it ...
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1answer
176 views

Add control variables in moderated mediation model in Mplus

Sorry for the silly question but I am very inexperienced in SEM I am testing a moderated mediation model with two serial mediators (M1 and M2) of the X-Y relationship, and also one moderator (W) of ...
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Question on Multi-level Categorical Variable

I have a question on the coding/use of categorical variables: In short, I have two control variables in an SPSS regression model. One is participant (15 levels, or participants) and one other ...
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When is it inappropriate to control for a variable?

I can think of at least one naive example. Suppose I want to study the relationship between X and Z. I also suspect that Y influences Z, so I control for Y. However, as it turns out, unbeknownst to ...
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Is ANOVA or ANCOVA more appropriate for an experiment with random assignment?

I understand that in observational studies, if we want to use regression for analysis, and if some variables are supposed to be a confounding variable, we should control for them in the regression ...
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Random forest analysis while considering control variables with predictor variables.

I had a question about using random forest analysis with my metabolomics data (~1000 metabolites) and interested in the relationship with age (continuous). Is there such a thing as controlling for ...
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Rank change based on the original rank?

My question is on how to "properly" weigh rank changes. For example, in the scenario of faculty placement, it is harder to go to a better university when you are already in a good university. In this ...
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Controlling for time (logistic regression)

I am a PhD student working on the use of Twitter during political debates. I am fairly new to the field of statistics so would really appreciate some help with the following problem: I am looking at ...
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Proving that paired time series are (not) correlated

I've got a dataset comprised of a bunch of "paired" time series, where the data in each part of the "pair" are dependent on each other, but I'm actually concerned with (dis)proving that the two time ...
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1answer
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Pooling samples that have no difference in design: asymptotic properties

Say I conduct a study and assign participants to one of two arms, but both are identical in design. The only real difference is the label assigned to the group, call them $X$ and $Y$. We assume that ...
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1answer
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Did I correctly “control” for my variables in this regression?

I am researching whether female representation changes the innovation output of companies. I have panel data of 30 companies over 10 years and "diversity, sales, r&dbudget, #employees" as my ...
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1answer
845 views

Logistic Regression with Moderation and Control Variable

I perform a Logistic Regression in R which looks the folllowing: logit <- glm(result~Condition+Strength, data = combined, family = binomial) I am mainly ...
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Control or confounding? A case with two correlated categorical and continuous predictors

Consider a case study which consists of two predictors (Date and IndBin) and one response variable (Count). One predictor is ordinal (Date) and represents the day number within a season. The other ...
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1answer
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Controlling for the influence of a third variable in a three-arm, prospective RCT

Thanks in advance for reading and chiming in, if you have any advice. I'm working on a project that involves testing an intervention that could increase HIV testing rates. Participants will be ...
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Do control variables need to have a correlation to both the independent variable and the dependent variable?

I have been wondering about this: Do control variables need to have a correlation to both the independent variable and the dependent variable? E.g. I want to check the effect of Education (...
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2answers
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At what level are covariates held constant in multiple logistic regression?

I'm running a multiple logistic regression with several continuous and categorical covariates. I was wondering how to interpret the results of each covariate if the others are held constant. At what ...
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1answer
3k views

Choosing control variables

I am designing a regression following the advice tho include control variables if they could have a causal effect on the dependent variable and if the variable is correlated with the independent ...
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Significant coefficient becomes insignificant after adding a control variable - not the other way round [duplicate]

I am doing a linear regression analysis and get a significant outcome when testing the effect of the IV on the DV without any control variables. When adding the control variable age, however, the p ...
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What is the difference between controlling by dividing by a variable, and inserting it as a predictor?

I have a dataset, based on forum conversations, with the following variables: count of emotional words count of cognitive words ...
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2answers
671 views

adding control variables in the regression in the experiment setting

After conducting the experiment and doing the statistical analysis, usually we run a linear regression $Y_i=\alpha+\beta X_i+\epsilon_i$, where $X_i$ is the treatment variable (randomly assign people ...
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1answer
63 views

Is it possible to compare 2 groups while controlling for something?

Is it possible to compare two groups (e.g., t-test, Wilcoxon, Mann-Whitney test, etc.) while controlling for something? E.g., I want to compare home ownership between military veterans and non-...
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Multivariable Regression on correlated / collinear variables

Let us consider a variable $Y$ on which we want to apply a multivariable linear regression on the variables $X_1$ and $X_2$. $X_1$ and $X_2$ are collinear by construction, with $X_1=ab$ and $X_2=bc$, ...
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Correlation analysis with compound variables: controling for a second correlation

We want to test for the existence of a correlation between a variable $X$ and a second variable $Y=ab$ ($a$ and $b$ being independent variables representing observational data). We know that the ...
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1answer
2k views

Control variables in instrumental variable regression

I have seen published papers include "exogenous controls" in their instrumental variables regression. Can someone explain: What is meant by "exogenous" in this case? The purpose of these "controls" ...
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1answer
249 views

Controlling for biased audiences in online surveys

For a long time I have been meaning to set up a bunch of online surveys asking a whole range of social questions and publish the results. I am well aware that there are various difficulties to ...
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Can Control Variables also be included as Dependent Variables?

I'm currently reading an academic journal (http://papers.ssrn.com/sol3/papers.cfm?abstract_id=2488863) which, in Table 11 of the paper, lists several control variables including: Returns Size ...
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Should I control for categorical control variables that are related to my independent variable in panel with many panels, short time length?

I am doing a panel study where I have a sample of persons $i=1...N$ (up to $N=300$), that have some personality dimension quantified as variable $x$, over a time horizon $t=1...T$ (up to $T=20$). From ...