Questions tagged [ancova]
Analysis of Covariance. This is really a special case of multiple linear regression, used in ANOVA-like settings with some continuous covariates in addition to the categorical ones.
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Advantages of MLM over repeated measures ANCOVA?
Hello StackExchange community!
My study group and I (M.Sc. in psychology) are currently studying for an upcoming exam and can´t figure out the correct answer to the question below.
Its neither ...
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Selection of covariates to control primary outcome effect in linear model
In my master thesis, I have to analyze mean differences of several outcomes in three classes and control the effect with max. 5 covariates available. Originally, I wanted to perform an ANCOVA, but an ...
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ANCOVA, ANOVA and MANCOVA with random effects, how do I perform this on SPSS? [closed]
Today was the first day I ever heard about mixed effect, fixed effect and random effect.
I am interested in how does one perform a repeated measure ANOVA, ANCOVA and MANOVA with random effects on SPSS?...
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ANCOVA or Linear-Mixed-Effects Model for a design with categorical within-subjects and categorical/continious between-subjects variables [closed]
I am trying to come up with a proper statistical model for my analysis. To describe my data structure / experiment shortly: There are two groups of participants (A and B) completing a simple task on ...
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Design of a Dental RCT in Which Patients Can Act as Their Own Control
I've been asked to help determine the design of an RCT. The design is primarily interested in the benefit of using a laser on some dental procedure in addition to a local anti-biotic and scaling, ...
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Calculating effect sizes for individual post hoc comparisons in ANCOVA
I ran ANCOVA with dependent variable IQ, independent variable field of study (3 groups: science, humanities, business), and two covariates (age and sex). I see that my result is significant (i.e., ...
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Question about running Quade's test instead of ANCOVA
Hypothetical scenario. Let's say I'm running 6 separate ANCOVAs. My independent variable in each is field of study (3 groups: science, humanities, and business). For each ANCOVA my dependent variable ...
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Question about linearity assumption in ANCOVA
I'm running ANCOVA. My dependent variable is is IQ, and one of my covariates is sex. I know that to perform ANCOVA you should be thinking that there exists a linear relationship between your dependent ...
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How to interpret scatterplot to test linearity b/w covariate and DV?
I'm doing an ANCOVA on a fictitious dataset of math test results (DV) by group (n1 = 50 online training; n2 = 50 no training) with previous math ability as a (covariate) to see if there is a ...
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Checking assumptions of ANCOVA
I'm trying to run one-way ANCOVA on my data set in R. My dependent variable is continuous, my independent variable is categorical with 4 levels, and my covariates are categorical: One with 2 levels, ...
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ANCOVA analysis
I'd like to perform an ANCOVA analysis for my study.
The following features:
3 groups and 1 DV (continuous)
ANOVA and post hoc analyses showed a statistically significant differences
There are some ...
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Between subject design, spread over multiple days
We have a between subjects design, testing for the impact of aesthetics on occupant satisfaction. Intervention is carpets vs no carpets.
The people participating in each leg (intervention vs control) ...
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ANCOVA with binary covariate
I am looking to run an ANCOVA with continuous outcome variable, looking at the effect of a categorical variable (race/ethnicity) and controlling for a binary covariate (treatment condition, values 0 ...
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How control for a pre-treatment outcome $Y_0$ if is a strong confounder while avoiding regression to the mean bias for treatment effect on $Y_1$?
I'm facing a dilemma in a pre/post cohort matching analysis for a healthcare intervention:
Matching on the pre-treatment outcome $Y_0$ (a continuous variable) will likely lead to regression to the ...
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Controlling for individual differences in a repeated-measures design?
I have been analysing a study where around 500 participants each were given a survey, so there were repeated measurements of each participant. Participants were male and female uni students who were ...
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How to identify variables
Good day. Basically, my study is about games' effectiveness between two groups. I have three assessments: pre-test and immediate post-test (to test academic performance) and delayed post-test (to test ...
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Sample size for adjusted-mean difference in ANCOVA design with covariate imbalance
I'm trying to make a function for sample size calculation of an ANCOVA design, based on a desired precision of the adjusted-mean difference between 2 groups (desired standard error), with p covariates,...
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How to assess the impact of confounding variables?
Recently I performed a comparative study where the participants had to perform different tasks using two different VR interaction methods: controllers and hand tracking. They also filled out a survey....
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How do I calculate p-value for trend across categories in R?
I am using R to make a table describing my dataset. My goal is to estimate the adjusted mean of a continuous variable across different groups (e.g. age groups, BMI categories) and calculate a p-value ...
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How to interpret results from the data if Levene's test is violated?
I'm doing ANCOVA analysis. So, the assumption of Levene's test is violated which means I have to run a non-parametric test. Does that mean I can't interpret other results that I obtained from the data ...
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Ancova with multiple interactions
I'm trying to quantify and test the trend in species richness with elevation. The thing is that I have multiple factors and I don't know if I can include all of them when fitting the linear model.
I ...
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Nonlinear dependence on continuous variable: alternative to ancova?
I have data that looks something like this:
I was hoping to run ancova, but the data is not linear in the continuous variable, and there isn't an obvious transform to apply.
However, each group is ...
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What is the difference CUPED and regression adjustment？
CUPED (Controlled-experiment Using Pre-Existing Data) is a variance reduction technique created by Microsoft in 2013 and widely used in technology companies. let Y is the target metrics and X is ...
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Should I use a two-way ANCOVA or three-way repeated measures ANOVA on my data?
I am trying to run a two-way ANCOVA on data from a multi-crossed design, looking at the effect of 4 treatments on the decay rates of 2 DNA target concentrations in moving water over time. Mesocosms ...
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How does variance-inflation factor creep into a chunk test?
In this question, the OP runs a “chunk test” and has a linear relationship between a variable in the restricted model and the variables in the chunk.
If this were a chunk of just one variable, that ...
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How to control for gender when looking at group differences with a 4-level factor (ANCOVA)?
So I have a dataset with 4 distinct groups, and I am trying to see if there is a difference between these groups on a dependent variable Y which is cardiorespiratory fitness. I did an ANCOVA and added ...
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Pre and post intervention (same subjects) with different outcome (successful and unsuccesful) as a result of the treatment
i have pre and post measurements of biodata (20 clinical measurements) taken before and after the treatment from a group of 30 people, out of which I have 20 successful and 10 unsuccessful subjects. I ...
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Baseline-adjusted ANCOVA vs baseline-adjusted LME
I'm a bit of a novice at this so please be nice!
Essentially, I want to know which method is the most statistically sound in application. I have two groups (allocation), two time points (pre/post), a ...
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Should be the baseline included in MMRM? MMRM vs. cLDA
In the cLDA (constrained longitudinal analysis) analysis the baseline value is already taken as a response, so it doesn't have to be included on the right side of the model.
But in MMRM ANCOVA (mixed-...
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should i use only main effect or include interaction for my ancova, not sure how to define my model
I am running an ancova, dv= "usc", between var=group, covariate = gender.
I am not sure if i should use * or + in my formula. also, if i wanted to add another covariate (say education), how ...
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ANCOVA or mixed-effect binary logistic regression
I am struggling to choose the right model. In the data, 30 people answered 10 questions with either "Yes" or "No". The participants are seperated in two groups (Sizes: 13 and 17 ...
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Post-hoc test for evaluating changes in baseline
I have two groups that recieved a different combination of treatment. For the first group baseline is 15.5 and for the second group it is 17.4. The difference in baseline after some time is −9.0±1.0 ...
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Mixed Measure Anova vs. Two Way Anova & Repeated Measure Anova?
hello!
I am attempting to determine if I should run a Mixed Measure Anova or a Two Way Anova & Repeated Measure Anova.
Essentially, I have a design where there are four treatment levels (t1, t2, ...
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ANCOVA with one factor/independent variable and two covariates in R
I did a study in which participants were randomly divided into 3 conditions, each of which completed a different memory test (with different difficulty levels). Additionally, all participants did an ...
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GLM: how to treat multiple variables that all measure a confounding aspect in a slightly different way?
For a response variable $y$ and predictor $x_0$, I have data for a number of additional variables $x_n$, $n = 1, ..., 7$. I would like to control for a confounder in my GLM, let's call it "size&...
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Understanding impact of significant covariable on treatment (ANCOVA)
I used paired sample t-tests to show significance on three dependent variables with one independent variable. All were significant in the experimental group and not in the control group. I controlled ...
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ANCOVA with two dichotomous IV and three covariates - how to interpret interaction between IV
As part of my thesis I am investigating how emotions influence food preference predictions between romantic couples.
I've run an ANCOVA with one continous DV ...
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What type of analysis to use for a pre-post test design with paired means and covariates (stata)
I am conducting a retrospective analysis of the efficacy of an intervention with "Therapy A." There is a baseline period and a treatment period, however, all the patients received the ...
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Justifying a smaller control group in survey study
I am planning a set of studies that are interlinked. The first study collects information from 400 participants (exposure group), then some psychometrics are performed to assess the questions. In a ...
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ANCOVA with all continuous variables
I have the following variables:
Psychological trait data collected at pre- and post-intervention
Fitness data (e.g., weight in kg), collected at pre- and post-intervention
I am interested in seeing ...
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What sort of test to use when the ANCOVA has a categorical DV?
I am carrying out some research, and I realised that my DV is going to be categorical.
I originally planned on carrying out an ANCOVA; I have 1 IV with three levels, 1 DV and 4 covariates. After doing ...
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Is it okay to leave a treatment group out of an analysis?
I am currently analyzing data from an RCT. The primary findings from the RCT have been published and we are now examining the data further. In brief, the RCT examined the effectiveness of a new ...
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Mixed ANCOVA SPSS Interpretation
Before I ask my query I need to explain some basic details with respect to my study.
Design: I have a mixed factorial design 2X2x2 with two within subject factors (having 2 levels in each factors) and ...
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Repeated measures ANCOVA interpretation – significant covariate/test day interaction
I am in the last phases of my master’s thesis, and came across a question regarding my data analysis results that I cannot seem to find a clear answer for.
For context, my data is from a randomised, ...
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Do there exist welch's repeated measures anova/ancova/manova?
Do there exist welch's repeated measures anova,ancova for unequal variances or does one have to run a mixed-effects regression or friedman test?
Is it possible to generalize this methodology to ...
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Is it justifiable or acceptable to only check for moderation only in the experimental groups not in the control group
controlled experiment we have 5 groups:
2 Control Groups (CG, passive and active)
3 Experimental Groups (EG, Doseage of the Intervention).
We also have two measurement time points T1 and T2 and ...
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ANCOVA vs linear mixed model in R, using different functions gives me different results
I have tried different packages, functions, libraries etc in R and my results differ, whether it be p values or F values or DF etc. This is especially true for my within variable (hemi)..
between: ...
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Linear Mixed Model with repeated measure design, continuous and discrete predictors, and continuous predictor partially nested under discrete factor
Let's say I have the following data frame where subject ID (random factor) is completely crossed with the two other factors: IV1 and IV2. Additionally, IV2 is partially nested (or partially crossed) ...
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Can I do an ANOVA while controlling for a categorical variable (an ANCOVA except the covariate is categorical)
I'm looking at nesting differences between 3 species of fish. These fish nest in colonies (all 3 species intermix in the colonies), and measurements were taken at several different colonies throughout ...
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Simple regression on subsets vs ANCOVA with interaction term
I'm attempting to predict a continuous variable as a function of one continuous variable and one categorical variable. This led me to an ANCOVA, but I've violated the homogeneity of regression slopes ...
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