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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What should be normally distributed for a two-way repeated measures ANOVA? R

When running a two-way repeated measures ANOVA, should: A) the independent varibles be normally distributed? B) should the scores between the variables be normally distributed? Overall: should the ...
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One-way ANOVA test with average values

I'm currently trying to run an ANOVA test on a pretty large data set, and I have everything condensed into a pivot table which spits out average times for each test and trial. If I just multiply that ...
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How to specify a repeated measure in a Mixed Effect ANOVA?

I am trying to run a Repeated Measures Mixed Effect ANOVA in R. However, the syntax of the code is really tricky and it seems like there is not a lot of clarity on how to run it as I do my research. ...
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Is it appropriate to perform ANOVA's on cluster group variable

I have completed 2-step cluster analysis on a data set and the result is that I have 4 cluster groups. The groups cluster around wellbeing variables - e.g positive affect, carefreeness etc. The ...
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What does the "adjusted by" mean?

"Matching of one group with specific exposures or outcome with a comparable group is frequently used in medical research to investigate the association between exposure and outcome." Ref ...
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Should this be an ANOVA or a MANOVA?

I'm fairly new to statistics and am struggling to figure out whether I should be using ANOVA or MANOVA for my research design: Participants will watch a performance together in one of three different ...
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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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Simple effect analysis following mixed anova with significant interaction effect

i am a little bit confused, as to which simple effects i need to analyze after conducting a mixed anova. I have conducted a mixed anova with time (pre-post-) as the within-subject variable and group (...
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What kind of study design is this and what kind of statistical analysis should be suitable?

I plan to conduct a study in which respondents will be asked to solve total 6 puzzles together. Is there a specific study design (name) for this? The scenario would be: First, ...
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How do I interpret this Scale-location graph based on an anova?

I ran an anova using 1 categorical factor with 2 levels (Habitat: 1 and 2) and 1 continous factor (leaf carbon concentration)as the explanatory variables. The response variable is continous (...
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How to treat a subject's possible preference

I have some animal preference data and would like some advice on treating it correctly. There are 10 subjects, and two trials dealing with a barrier product. The subjects were allowed to select one of ...
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How do we report a anova() of multiple model comparisons in R?

My question is pretty similar to this one, but I don't seem to get an F-statistic. Hi, I know that we would usually report an ANOVA result as ...
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How to implement factorial experiment design? [closed]

I am trying to analysis data for my thesis so a factorial experimental design has been suggested. The problem is I have done data collection process befor designing an experiment and now my sample ...
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Is it possible to compare different frequency distributions with ANOVA and how would you go about it?

For example if I have three different samples of red blood cells, and I created a frequency distribution of the red blood cell size for each sample how would I run ANOVA to compare the differences ...
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First test nonsignificant; second test significant. Do I need to include repeated testing as a factor in ANOVA?

I am running a repeated measures ANOVA for my data set. Our rats completed 8 training sessions in 2 conditions (within-subjects; 16 sessions total). Then they completed a test - the same test in each ...
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Post hoc tests: correct for all possible comparisons, or only those conducted?

When conducting a post hoc test e.g. after an ANOVA and correcting for multiple comparisons, do I need to correct for all possible tests or only those that I am interested in? I've seen contradictory ...
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Understanding estimates of categories of qualitative supplementary variables when doing PCA using FactoMineR package in R

FactoMineR package is helpful when doing PCA and much more. Coming across the output using dimdesc() function and looking at the estimates of supplementary ...
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Anova with stratified Cox model

I'd like to use anova to investigate which variables are important to my Cox model outcome. I tried using anova from ...
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Reason for the error in ANOVA: models were not all fitted to the same size of dataset [closed]

I have been running with this error for a long time and I have been failing to fix it. Does anyone have an idea? ...
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Two-way ANOVA to test difference in a 2:1 matched observational study

Apologies in advance if this is a silly question, but it's the first time I tackle a sample with these characteristics and wanted to have some feedback on the best way to proceed. I've been given a ...
1 vote
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cannot reproduce the example for nested anova

I'm working on the example for nested ANOVA from the Handbook of Biological Statistics. Copy-pasteable data can be found at https://www.biostathandbook.com/nestedanova.html and below shows my ...
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How to incorporate repeated measures (pre and post experimental conditions) into three-way ANOVA?

I'm analysing data from an experiment I conducted last year with one treatment group and one control group, each imposed on two plant varieties in five pot sizes. I took two measurements from each ...
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I need a simple but indepth explanation of what a perMANOVA is and how to use it

I've been told by the supervisors of my honors project that I'll be using a perMANOVA to analyze the differences in invertebrate abundance and diversity across 4 different sites, some of which have ...
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Overall effect for non-binary categorical variable, Cox

There are many great answers on Cross-Validated explaining that the p-values for cox.zph (or other regression models) in R refer ...
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how can I design an experiment through factorial with 3 sample size? [closed]

I am trying to analyze data for my thesis so a factorial experimental design has been suggested. The problem is I have done the collecting data process before designing such an experiment. I have just ...
1 vote
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R: What's the correct way to run an ANOVA with a continuous DV, one continuous IV, one categorical IV, and a blocking factor?

I'll TL:DR this in case if it's too much to sort through. Depending on method: either lmer(), lme(), or ...
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How to compare variances of multiple independent variables (to themselves) pre vs post treatment to determine treatment efficacy?

I have 10 different subjects and observations of their blood pressure before and after treatment. Treatment occurred at different times and at different ages in the subjects lives. I'm interested in ...
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1 answer
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How to do pairwise comparisons for Kruskal Wallis test?

If the null hypothesis in the Kruskal Wallis test is rejected, How can we perform pairwise comparisons? Can we apply Dunnett's Test for that?
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Running an ANOVA on a likert scale question

My participants heard two kinds of stories i.e. two conditions and rated two protagonists in each of these stories or conditions on a Likert scale of -5 to +5. So I had two conditions, eight stories (...
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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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Learning Linear Mixed Models from a ANOVA background

It is my first question, and I would like a recommendation from the community. I am having trouble understanding Linear Mixed models. I have already tried to read some books and also tried some online ...
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Can I test for differences in frequency data?

So I am investigating if an animal is being sighted more frequently in recent years. I have data that includes group size of this data - ie. year Group Size 2018 4 2018 26 2019 10 2019 46 2020 9 ...
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Bonferroni (or BH) correction for multiple t-test?

I'm studying the kinematics differences between males and females examined at two different specific walking speeds (slow/fast). Specifically, I'm exploring: a) slow speed vs high speed (dependent t-...
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What do the p-values for each variable in the output lm() in R mean?

I have a rudimentary understanding of statistics so please forgive me for my ignorance with technical terminology and potentially dumb questions. I am trying to use the function lm() in R to determine ...
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Test for significant differences among multiple group

I am not sure whether a test for something like this exists. So I have multiple groups 1,2,3,4.... In each group there are many measurement values. ...
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Specify an lmer model for fully crossed data with replications

I have experiment data with multiple independent variables: shape - 2 factors color - 2 factors ...
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What should I report on a 3-way ANOVA with a significant 3-way interaction effect?

I'm using graphpad prism to analyze some research data. The study design has 3 factors (Sex x Cardiac Anomaly x Exercise workload) for a variety of parameters. I don't use 3way ANOVA very often (and ...
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Pre-post analysis on stores which do not start treatment at the same time

I have a control and experiment group stores where the treatment on experiment group stores doesn't start at the same time. I am thinking of doing a rmanova. But i am not sure if it's the right way ...
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Which test do I need to use in Rstudio? [duplicate]

I need to analyse how two different factors (the time of the day and the background of subjects) influence the stress level of people who took part to an experiment. The stress level is expressed on a ...
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Not sure if i should be doing a type III anova

I was initially using the following anova formula in R aov.out <- aov(column_name ~ core * ethnicity, data=mydata) However i noticed that my dataset is quite unbalanced : In light of that I tried ...
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What is the difference between Partial Eta Squared and Partial R Squared in factorial repeated ANOVA?

I carried out an repeated measures ANOVA in SPSS with two within subjects predictors, and requested for measures of effect size. SPSS provides partial Eta Squared as a measure of effect size, but I ...
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permutation test for mixed effects 3-stage nested design

I have a dataset that uses a 3-stage nested design, and I want to perform an ANOVA. I used lme() from the nlme package in R to fit a linear model, but I found that after doing a shapiro-Wilks test, ...
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How to use GAMs to test whether a prediction model is properly calibrated in R

Suppose we wish to test whether there is an identity relationship between some observed values and the predicted values from some model, and allow for non-linear deviations from this hypothesis. This ...
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Relationship between P-value (ANOVA) of subsets of dataset

I'd like to ask this as a general question, but it originated from a specific situation I came across. Let $\mathcal{D}$ be a dataset. Each point has two attributes, $X$ and $Y$, and a corresponding ...
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Bootstrap Anova and posthoc comparisons for non-normal data

I have a dataset like the following (n=1400): ...
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Alternatives to ANOVA for kill assay [duplicate]

I'm trying to find an appropriate test to compare my data. I ran an ANOVA to compare different drug concentrations' effects on bacterial population count at different time points. I believe that the ...
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LMER returns errors, but Repeated Measures ANOVA on the same data doesn't, why?

everyone! So, I've been trying to fit a LMER for my data, which I fully described in this post . This post, therefore, is a follow-up from the previous one. There's something intriguing me, I don't ...
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Why Hotelling's $T^2$ is taught in the book but it is not used anywhere so far?

I have seen various multivariate statistics book covering Hotelling $T^2$ statistics. However, when reading medical journals and papers, it does not show up anywhere. Q1:Is this test of any practical ...
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Two way ANOVA or ANCOVA for hibernation data [closed]

I am looking at differences in torpor bout lengths (hibernation times) for bats and my main grouping factor is WNS (disease) status. My study area is used for one analysis, and I basically want to do ...
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Significant interaction in repeated measures ANOVA becomes insignificant with a covariate (SPSS)

I'm finishing my masters' project and have some results that are confusing me! I ran a repeated measures anova as 2 (valence - neutral or negative) x 4 (Task 1-4) This showed a positive main effect of ...
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