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Questions tagged [anova]

ANOVA stands for ANalysis Of VAriance, a statistical model and set of procedures for comparing multiple group means. The independent variables in an ANOVA model are categorical, but an ANOVA table can be used to test continuous variables as well.

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In a within-subject experiment design, I have 2 independent variables and 1 dependent variable. Which statistical test do I use?

I have collected pupil size data in a pupillary conditioning study (with a baseline correction applied) in which I want to compare the area under the curve (AUC) in a pre-training control to the post-...
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How can I test significant differences across multiple categories in different dataframes?

I have very basic statistic knowledge and would like to hear some suggestions to analyze my data. I've three dataframes as displayed below: ...
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PostHoc Tests after two way anova in R [on hold]

I have a data table with 2 explanatory variables: Noise, with 2 levels ("Exposed", "Unexposed") Voltage, with 9 levels The dependent variable is Delta Cm So, after checking Normality and variance ...
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Can I do moderated multiple regression with Process by Andrew F. Hayes when my moderator variable has 3 categories?

I have only seen it when the moderator variable has only 2 levels/groups/categories (dichotomous). What if my moderator variable has 3 levels? Should I just use a two-way ANOVA then since it also ...
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Conditions of Mixed, Random, fixed models

Under what conditions is a design said to be : 1. Fixed effects model 2. Mixed effects models. Or can anyone suggest a suitable pdf of the above content?
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What type of test do I use in G Power?

I've got 1 IV with 2 levels (within-subjects) and 4 VD's (with 7 levels). What type of test do I use in this case ? Thank you
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Experimental Design Fixed Effect Minimal Detectable Difference

How does one determine the minimal detectable difference for a fixed factor/interaction in a general balanced experimental design? For example, I would like to be able to recreate Appendix 12 of ...
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Comparing mixed models - understanding anova output in R

I am comparing mixed models in R using anova. My model m5 has one of the variables from model m4 omitted and I want to compare the 2 models to see if the dropped variable was significant. Comparing ...
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Calculate $\eta^2$ for repeated measures anova with lme4 in R

I know this is a subject of controversy, but I'm not interested in why p-values and effect sizes are bad but how I can calculate the latter based on the lmer() ...
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Regression using previous years results

Is it possible to make a linear model non auto regressive using previous years observation's. For example I have a student score, and I have 3 contributing variables (subject scores e.g. science......
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what type of research design should I choose?

I am trying to do a research proposal where I planned on doing a pretest-posttest experiment on 2-3 groups of subjects (measure baseline indicators of anxiety, depression, self-esteem, body ...
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non-parametric alternatives to anova

Hello I am doing some stats on some research I did and was having trouble picking the correct statistical tests to use. The question I am trying to answer is, I have two cell types (I, II) and two ...
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R - Help interpreting GLM and ANOVA output

Am I correct in understanding that the effects of flood.level and plant.species are significant predictors of Inv.Simpson (my measure of diversity)? Is it also correct to say that the effect of ...
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Account for covariate after predictor in ANCOVA?

I've been thinking about ANCOVA a bit and I didn't find anything on this particular issue. One of the most critical assumptions is that the predictor is not correlated with covariate. This is pretty ...
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How to write up a Tukey Post Hoc Finding- please

How do I interpret these results into a Post Hoc Tukey HSD? TIA.
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RCT statistic help please

I am wondering what statistics to use for the following randomised controlled trial. A between groups design with a control group, group therapy A, and group therapy B. I am measuring pre and post ...
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From Anova table to linear model coefficients

I understand how to construct an ANOVA table and compute the various Sums of Squares. My query is : How do we go from Sums of Squares to the effect sizes ? Can someone please explain ?
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Pursuing meaningful questions about pre- post- intervention outcome measures in single condition treatment

If you are not fortunate enough to have a control group and have a single condition only, what meaningful questions can you ask about the change in pre to post intervention scores? If ANOVA or ANCOVA ...
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P-Value in Shapiro-Wilk test

I've read that if this p-value is less than 0.05 (for a 95% confidence interval), the null hypothesis that the data comes from a normal distribution must be rejected. However, in the following ...
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R: Anova() from car package not displaying F value [closed]

I am doing an anova and would like to get the F value as well. So far it is still doing a Wald chisquare test instead of an F-test. I don't understand what I am doing wrong. Car package version is 3....
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What statistical test should I use for moderation?

I am hoping to test an interaction effect, though being new to statistics/quant research in general, I am a little unsure as to which test would be most appropriate. I have read around using ...
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Why use Linear Mixed Models instead of Repetead Measures ANOVA?

Well, here's some background before the question: I have an experiment where I evaluate the heart rate of subjects in 4 different conditions (4 time points). The subjects also answer a psychometric ...
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Adjusted Mean of Variable given Single Covariate with Weak/Moderate Relationship

Say I have two variables X and Y, each a data set with corresponding data points 1 through n. These two variables have some casual, small but significant relationship (low r value). Then I am unsure ...
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How to calculate significance for an A/B test for average revenue per daily active user over a 1-week test period?

One simple approach is to use "per active day" metrics. e.g. "revenue_per_active_day" . However there is a fundamental flaw with this approach. e.g. during a 7-day period, let's say user 1 is active ...
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Interpreting ANOVA f-test for model comparison

In the book ISLR, there's a lab activity which compares the nested models. ...
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Non-parametric alternatives for a three way nested ANOVA?

I am a student working on a graduate degree in the natural sciences. I am looking for advice on generals approaches and examples (R code and example data) which I might be able to follow to get ideas ...
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comparsion of treatment groups based on different controls

I have experimental results from two days where I wasnt able to keep the same conditions from day1 to day2, so I have two sets of data: control day1 -- 2x treatment groups day1 control day2 -- 2x ...
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What types of problems can an unbalanced design cause?

I have a between subject factor called group (with three levels) and a within subjects factor called stimulus (with two types of stimulus). Du to limitations out of my control, there are an unequal ...
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Repeated measures ANOVA study - calculating the sample size

I’m soon conducting a study on healthy volunteers. I’m interested to know how 3 different body positions is going to affect the cross-sectional area of a neck vein measured by ultrasound. (Primary ...
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ANOVA does not produce results only dots

Question: I am trying to use an ANOVA on the following variables, but the results are only dots. How come? Dependent variable: grades (0, 1) where 0 = fail and 1 = pass Independent variables: ...
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Power analysis for same model as “ANOVA” vs as “multiple regression” yields different results

I have seen posts that said ANOVA and multiple regression are theoretically the same. But if this is really the case, does anyone know why the G*Power (Linear multiple regression vs ANOVA) gives ...
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Unbalanced Two Way ANOVA

I am attempting to finish my stats on my Master's thesis and am having difficulties with which statistics test I should be using, and how to go about doing so. I have collected chl-a samples at 15 ...
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When to use blocks?

I am currently studying Random Complete Block Designs (RCBD) and I would like to ask a question. I cam across an example where we were able to conclude with the RCBD as significant, but regular ANOVA ...
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ANOVA OR ANCOVA?

I have 3 different groups of people that completed a language task. Some individuals took a drug and some did not. I would like to investigate the effect of the drug on performance in the different ...
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Analysis of Variance table (lm function)

I have a dataset dataset take has compnds1 (chemical compounds from 1st harvest), compnds2 (chemical compounds from 2nd harvest), method (=treatments, there are 4 treatments, 1 is control, 2 is hydric ...
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Can I do multiple ANOVAs without correcting for multiple comparisons?

In my study I have one repeated measures factor that I manipulated on two levels and one between-subjects factor that I manipulated on 3 levels (three groups), resulting in a 2x3 design. I also have ...
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How to analyse an individual difference interaction with a mixed design - SPSS

My experiment has two factors. One is between subjects (3 levels - no, low, or high distraction) and the other is within (2 factors - tasty crisps and untasty crisps). I've already analysed this, but ...
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mixed ANOVA alterantive for inhomogeneity of variances in SPSS

I am trying to compute a mixed ANOVA with one within-subjects factor (two different types of stimulus categories) and one between-subjects factors (three participant groups). My problem is that the ...
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Ancova for unequal variances [duplicate]

What is the best way to compare two non-homogeinous populations (Levene's) with covariates (e.g. age). I know ancova assumes homogeneity. Is there a way around this? Many thanks
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Time course experiment with treatment, use two way RM ANOVA with post tests or multiple ttests?

I have time course experiment with time and treatment as variables and want to compare treatment differences at specific time points. Would it be improper to use a unpaired ttest at a specific time ...
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Interaction not significant anymore in ANCOVA, but in ANOVA

I have a significant interaction $A\times B$ in my regular mixed ANOVA, but when I add a covariate, the effect $A\times B$ is no longer significant, but the interaction effect with the covariate $A\...
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How to report robust anovas (WRS2::t2way and t3way): no df

I have done experiments with a parasitic wasp species, comparing its life table parameters (response variables: longevity (in days), number of offspring and development time of offspring (in days)) ...
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Type 1 Error correction for multiple comparisons: ANOVA vs multiple regression

After looking into Type 1 error correction protocols for multiple comparisons in ANOVA vs. MR, I found two (conflicting?) messages. The same Type 1 Error corrections that apply to comparisons in ...
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Taguchi Designs for differential gene expression

I plan to do a differential gene expression using RT-qPCR of 10 genes on 3 strains cultured in different enviormental conditions of 3 factors (2 levels each one). In order to do so, I want to follow a ...
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Computing a DV for a 2x2 study design

I'm conducting research for the first time (for my master thesis) and have some trouble. I have sent out a questionnaire to research mortality salience effects on purchase intention and price ...
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How to deal with unequal variances in repeated measures ANOVA

Angry Birds is a video game in which you fire birds at pigs. A (fabricated) study was set up in which people played Angry Birds and a control game (Tetris) over a two-year period (one year per game). ...
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Analyzing and interpreting main effect in repeated measures ANOVA

Angry Birds is a video game in which you fire birds at pigs. A (fabricated) study was set up in which people played Angry Birds and a control game (Tetris) over a two-year period (one year per game). ...
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1answer
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Calculating normality for a two way ANOVA with repeated measures

I am trying to calculate if my residuals are normally distributed for my two way ANOVA with repeated measures on Rstudio. However, all the tutorials I find seem to specific to one way within ANOVAs ...
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testing normality for a two way anova, residuals as well as each sample? [duplicate]

to test a two way ANOVA do you have to test each sample for normality as well as normality for the residuals?
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What is the point of a permutation F-test when all you need is one F-test for one-way ANOVA?

Say you have three groups, and each group has 5 observations. You can figure out if there is a significant difference between means with a simple one-way ANOVA. I read in my nonparametric book, one ...