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.
204 questions
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Interpretation of slope coefficient when a variable appears in multiple powers
In a multiple regression, how do you interpret the slope coefficient of a variable if some other power of the variable, say, the variable squared also appears as an explanatory variable, i.e., suppose ...
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How to compare 5 groups on categorical DVs with covariates in SPSS?
I’m new to statistics and working in SPSS. I have a 5-level categorical independent variable and several categorical dependent variables, some binary (yes/no), some with more than two levels. I also ...
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Compute difference in repeated-measures values, while controlling for another variable
In our experiments, we measured two types of metabolic rates - Baseline metabolic rate (BMR) and Summit metabolic rate (Mcold) on birds, such that each individual bird will have both BMR and Mcold ...
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Seeking advice on bad control when the relationship is indirect (overcontrol bias?)
I’m working on a project where we’re trying to estimate the impact of country fragility status on project outcomes. We have data on the total grant funding allocated to each project, which we’ve been ...
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Control variable on same level as fixed effect
There is a panel dataset with daily observations over two years and a control variable that changes on a monthly level and is the same for all units, so for all units within a month it takes the same ...
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Should All Variables Have Adjusted P-Values in Multiple Hypothesis Testing or Just Hypotheses-Relevant Variables?
I'm currently working on a project involving multiple hypothesis testing. I understand the importance of adjusting p-values to control for Type I errors, but I'm unsure whether I should adjust the p-...
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Change score as predictor
I want to see if a change in an independent variable (T2-T1) predicts another variable at T2. For example, higher increases in cognitive impairment over 1 year for people with dementia predict lower ...
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Multicollinearity when controlling for a variable
I have a few questions about multicollinearity in my data: I'm looking at a certain type of lesion seen on MRI scans; for each patient I know the volume of those lesions and a metric that captures the ...
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Impact of Covariates on ANOVA Results
I am conducting an analysis using ANOVA with covariates and encountering significant results. However, when I remove the covariates, the results are no longer significant. Here are the details of my ...
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Comparison of 2 groups with covariate
I compared 2 groups and found that their test scores are significantly different. However, I also found that they are significantly different in the mean age. I want to see if the scores between the ...
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Running a Negative Binomial Regression with Overdispersion
I am not an expert on SPSS but have been developing my skills and believe I should run a negative binomial regression on my data, though I am not certain.
I am testing the number of days people go ...
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Regression in sex differences multiple dependent variables
If I want to examine sex differences in three variables, lets say academic attainment, study motivation, and a variable that is categorical. How should can I fit these variables with OLS regression? ...
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Is every fixed effect a factor in the model?
Participants received one of three sets of instructions and each completed the same two unique questions in a randomized order. I have a 3 (instructions type) x 2 (question) mixed effects model with ...
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randomisation issue/crisis
I have randomized into three groups using a randomization aid and groups were examined at 2 time points. however in the analysis found that there was a significant difference at baseline in one of the ...
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Can covariates be included in multiple regression?
I am interested in understanding if two predictors variables are associated with treatment outcome (DV). I included two covariates that 1) differed across my levels of IV (age) and 2) another that is ...
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