# 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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### sample size calculation for 4 groups means

Suppose that I have 4 groups means:18,13,16,10, and 4 standard deviation:10,9,9,8, and α=0.05，β=0.1, how many samples do I need? I'm trying to calculate the sample size using ...
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### Post hoc on mixed model ANOVA with one fixed variable on random independent variable in r

https://www.youtube.com/watch?v=FuiUvwflkVQ In essence, I want to do the exact equivalent to what this video does, but in R rather than SPSS. So far I've used the following code, where DV is my ...
1 vote
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### Noncentrality parameter Repeated-Measures ANOVA - formula vs. G*Power

I am trying to figure out the correct expression for the noncentrality parameter $\lambda_{ws}$ for the within-subjects effect in a one-way Repeated-Measures ANOVA with $k$ trials/groups. Comparing ...
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### When is single factor ANOVA regression checking out for model diagnostics?

Consider a simple randomized experiment with 4 treatments(no control) where the outcome of interest is difference between pre-treatment and post-treatment count. I want to conclude 4 treatments does ...
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### How to understand the calculations behind a robust mixed factorial function in R, and the implications of running it? Example provided

In "Discovering Statistics Using IBM SPSS Statistics" Andy Field recommends using Robust versions of existing statistics in situations where not all assumptions are met. I'm running a 2x3(...
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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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### What's wrong with my code for ANOVA test in R? [closed]

Could someone help me see why my code in R does not produce the correct output or do I have a misunderstanding on ANOVA test? As you can see, there are three ...
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### Linear mixed model with unstructured repeated measures

I have a dataset with some growth measurements pre and post vaccination and 3 different groups (3 different types of vaccine) so there are both a within (pre/post) and between factor (group). Problem ...
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### Significant Levene-Test in Mixed ANOVA

I conducted a study to investigate the effect of instagram profiles on mood. Therefore I created two profiles on instagram and used a pre-post-measurement of mood (PANAS-scale). Participants (N=130) ...
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### Which stastical test should I use?

I have 10 participants who were asked to rate (from 1-5) 30 statements. I then asked each participant to assign each statement one of three categories. I want to establish if there is an relationship ...
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1 vote
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### Formal name for research design: repeated measures, 1 varying treatment condition, 1 constant treatment condition

I'm coming from a background with regards to randomizing treatment and just conducting measurement at one point in time. In my current setup, there are just four groups of interest: A control group (C)...
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### what would be a more appropriate statistical test for this repeat-exposure experiment?

I have conducted an experiment where fish are exposed to different concentrations of a substance and then several metrics are measured (swimming speed, etc) in order to assess the substance's effects ...
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### accounting for multi-scale spatial dependency in samples analysis

I have a spatially nested dataset as follows: 5 samples per cluster 5 clusters per plot 4 plots per site (2 habitats per site, 2 plots each) 7 sites overall I have: 5 samples * 5 clusters * 4 plots * ...
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### Is it valid to run a one-way anova with just a significant interaction term (specifically for Welch's Anova)?

Why would I run a two-way anova (interaction is significant) if I get the exact same results from a one-way anova with just the interaction term? Would it be valid to create a new term for the ...
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### Which stats test to use? Multiple Independent variables?

I'm working on a research project without much of a stats background so I need some help with figuring out which stats test to use currently. I think I have multiple dependent variables to look at, ...
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### Experience with Kruskal-Wallis versus Zero-Inflated Kruskal-Wallis as nonparametric alternative to one-way ANOVA

I have a data set of 1 categorical predictor (4 levels) and one non-negative continuous response variable (listed as "aphidleaf in histogram). The response variable is not count data and the ...
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1 vote
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I am sure that this is a simple question, but I can't figure out what my mistake is. I am doing an ANOVA project using car::Anova. I presumed that the TSS would be ...
1 vote
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### Nonparametric mixed-design ANOVA

I have an experiment design with one "within subject" factor and one "between-subject" factor. So I have to use mixed-model ANOVA, but empirical distributions are not approximated ...
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### When the type of test does not fit the research purpose

My research aims to find whether the type of images that my participants were exposed to affected their altruistic behaviours (yes, no) + whether their gender had anything to do with it. My dilemma is ...
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### How to test if each of the means from each treatment is significantly difference from 1?

Presented are sample data. There are three factors A, B, C in the dataset. (a) I want to test if each mean is different from 1. The points also have nested random ...
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### Two-way ANOVA (2x2) interpretation for non-significant values

I'm a statistics beginner and for my research, I'm looking into the effect participants' body image (positive/negative) and an advert model type (thin/plus-sized) have on participants' view of their ...
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1 vote
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### Verify relationship between a categorical and numerical variable

I have got some data about movie directors and number of cuts per minutes in their movies. I whould like to verify if there is any relation between this two variables. I have tried looking at the mean ...
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1 vote
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### Statistical test on percentage difference of a continuous variable and a binary varable

I want to run a statistical analysis on the gender pay gap data published by EU (https://ec.europa.eu/eurostat/databrowser/product/page/SDG_05_20) at a specific year, this data have the following form:...
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### Need help figuring out what statistical test to use (ANOVA or MANOVA)

I am trying to figure out what statistical test I need for my eye tracking study. I have 2 dependent variables: Dependent Variable 1 is continous (gaze behaviour, which is subdivided into fixation ...
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### Linear regression: F-test for lack of fit (using ANOVA to test regression model) - intuition?

This is the data set: https://raw.githubusercontent.com/FlorinAndrei/misc/master/stackexchange_attach/normtemp.csv I'm looking at a simple linear regression. The data is quite trivial. ...
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### ANOVA: crossed or nested

I wish to run a factorial design of experiment (DoE) to investigate the effect sizes of many factors. In my opinion the evaluation of the data depends on what I am comfortable to assume. If I am ...
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1 vote
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### R: lmer test the fixed effect by anova(Model) or anova(Model, model2)?

I have read some tutorials about doing ANOVA to linear mixed model. However, I've faced some problems with testing interaction, main effects, etc. This is what I used to do: Test interaction & ...
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### Comparing Variance of Random Slopes Across Categorical Fixed Effect

When fitting a random slopes and intercepts model, what is an effective way to test whether the variance of the slopes is different at different levels of the fixed effect? For example, image a ...
1 vote
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### Is it possible to compare means of pre & post intervention questionnaire for only 3 participants?

I am completing my dissertation which was to determine if a 6-week expressive writing intervention would reduce aggressive behaviors & increase emotion regulation in students. My first variable (...
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### Statistical test across multiple subjects with multiple trials (under multiple conditions)

I have some behavioural data that I am trying to analyse. I am not sure about the correct statistical tests to run to answer my scientific questions. I have a group of subjects. Each subject is ...
1 vote
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### alternative to ANOVA or simplifying approximations for multi-factor,, batch design with binomial data (advanced beginner)

this is my first post. I did already read various didactic materials and related posts here, but still had trouble figuring this one out. Sorry this is so long but I am trying to be as specific as ...
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### Can we run ANOVA for estimates?

So , I am currently working as an Intern for Government Statistical Organization that does sample surveys & presents estimates on various aspects. My work is to present some statistical analysis ...
1 vote
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### ANOVAs from SPSS and R report different degrees of freedom. Which are correct?

I am conducting a reanalysis of some data. The dv is continuous (beta value ie neural activity) and the iv is categorical (position) with three levels (1, 2, 3). There are 126 observations. The ...
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### How can I make contrast codes that satisfy the conditional for orthogonality?

I am trying to contrast code my categorical predictor variable, but I cannot produce contrast codes that satisfy the condition for orthogonality. According to Judd, McClelland, and Ryan (2017), the ...
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### Statistical analysis of dose effect on seed germination percentage data - Logistic regression?

I am trying to conduct a statistical analysis on seed germination data. Effect of 4 different plant extracts on seed germination is tested. Seed germination follows binomial distribution, as it is ...
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### What analysis to use?

I performed an experiment about tacile localisation where 20 participants were measured on the same 4 conditions. There are 2 factors: Conditions(crossed and uncrossed) and orientation (near, far). So ...
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### Multiple one-way repeated measures ANOVA vs two-way repeated measures ANOVA

I'm confused what should be the proper test for my data. I measured muscle forces of subjects at different frequencies (same 9 frequency levels for each subject) over three different time points (T0=...
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### Comparing group means with uneven number of repeated measures

I have data on N different athletes each of which belongs to one of four groups. Each athlete was tested k_i times, i=1, ..., N. Unfortunately in general k_i != k_j for i != j. As far as I'm aware, ...
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### Do I need to perform a post hoc?

I am performing a mixed between-within ANOVA with 2 groups at 2 time points. There is a significant interaction for MET levels, including a main effect for time and a main effect for group. Do I need ...
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### Analysis of variance with two empty groups: alternative?

I have treated a species with two treatments: salinity: five different concentrations a pollutant (control and two different concentrations) organisms grown with the two lowermost concentrations of ...
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### Range based GRR versus ANOVA

In my company we want to assess suitability of a gauge system to measure a certain quantity. The variance of that quantity when repeatedly measured on the same piece should not exceed a certain ...
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### Is there a non-parametric form of a 3-way ANOVA?

I am currently in the process of writing a publication about the home range of cat shark species in South Africa. However, I am currently struggling with how to create an interaction model of shark ...
1 vote
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### Three independent variables + moderator (started with three-way anova but not sure about it)

I have a conceptual model with 3 regular independent variables and one dependent variable. Next to those three independent variables, I have another moderator variable possible affecting the ...
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### Classifying year as a categorical variable + ANOVA

I've been debating for long if year is a categorical or numerical variable (by year I mean 17 discrete values from 1925 to 1941). I need to test if: a) time has a significant impact on the price of ...
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### Model selection for $4\times 2\times 2$ factorial design in R

I have read so many books, forums, and sites that I have completely confused myself. Originally, my design was a simple 4x2 factorial with two categorical predictors, but it has gotten more complex ...
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### Can I simplify a repeated measures Anova with only 2 time points?

I have a scale variable, collected in 2 separated times, t1 (pre-test) and t2 (post-test). My question is, must I use a repeated measures Anova, or can I use a basic Anova with only one factor: the ...
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### Mixed model without fixed intercept- Numerator df for Type II and III ANOVA (lmerTest vs Proc Mixed)

It comes to my attention that there is a discrepancy between lmerTest and Proc Mixed for the numerator degrees of freedom (df) for type II and III ANOVA. This only occurs for mixed model without fixed ...
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### Interpreting the output of sppba(), sppbb(), and sppbi() in R

I'm trying to run a robust mixed ANOVA with a between groups factor (2 levels) and a within groups factor (3 levels). I'd ideally like to be able to set and run planned contrasts, have a full set of ...
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