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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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Degrees of freedom in a linear mixed model (or ANOVA) - Categorical factors versus continuous numbers

I have data from 20 individuals. In general, each individual has measurements (i.e., called Value below) from the Left and Right arm taken at different months in ...
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Degrees of Freedom in 2k factorial design

I am working on a 2k factorial design experiment, and got stuck at one point. If the suppose there are only 2 factors A and B (K=2) each with only one replicate each. This means n=2. Then according ...
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using anova to compare two linear models of unequal sample size: error [migrated]

Here is an example of what I want to do, with a randomly generated number set: a<-runif(100, min =0.5, max=1); b<-runif(100, min = 0, max =1); c<-factor(rep(c("High", "Low", "High", "High")...
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factorial designed study within between

IV1 : alcohol use, IV2: breathing exercise (both of them within subject variable) IV3: gender (between subject variable). My research question is that: ''Does alcohol usage and breathing exercise's ...
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Pre test post tes control group design with within subjects

My research question is: ''Does alcohol usage and breathing exercise's effect on reducing excitement differ in women and men ?'' I have 2 within-subject variables: breathing and alcohol use, and 1 ...
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Performing repeated measures ANOVA on unstacked data in R

I am trying to do a repeated measures ANOVA on unstacked data for my experiment. For background, my experimental design is as follows: I have 160 stimuli divided evenly into 8 counterbalanced list, ...
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Repeated measures anova with 3 groups

I have a dataset with 3 groups Tuni, Sal, and Ohda. I have two timepoints for each, time 30 and time 60. I want to do a repeated measures ANOVA with posthoc tests for group*time in SPSS. I have also ...
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Generalization of one-sample t-test for multiple groups

If I have some data*, and want to test the hypothesis that it has a given mean $\mu_0$, I know of the possibility of using a one-sample t-test. Here, $\mu_0=0$ could be the null-hypothesis of a ...
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Interpreting aov output with lm input in R

I need help interpreting the results from an anova which was run on a lm. The data are bird counts per year by state. Here is a reference picture: Here is my code for the linear model followed by a ...
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How do I calculate the p-value from an ANOVA from R-Studio?

Don't really know how to interpret this! I am so confused and I tried to follow the examples but I am confused.
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Finding Correlation coefficient from ANOVA/regression

How would you find the correlation coefficient from given Sum of Squares values (Regression and Error) and regression values - slope of the estimate and standard error? Any help would be appreciated....
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Interaction between categorical and continuous variable

In my dataset, I have to test the effect of humidity on the height of plants. However, we have an extra effect which is nitrate on height. Each plant had a nitrate measurement but we had one group in "...
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Possible to have main effects and interaction in 2-way ANOVA?

In a 2 way ANOVA, can you have a significant main effect for each IV and an interaction? Why should caution be used when interpreting main effects if you have an interaction?
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Significance test suggestion for two factor design

i have been collecting data in 4 sites, in each site i performed 3 random counting of one species of fish abundance in two habitats: rock and sand. Furthermore, i have been recording presence/absence ...
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Repeated Measures ANOVA with two factors

I have 300 patients with heart problems (2 groups/types of problem) that have completed the questionnaire SF-36 (8 scales), before and after the surgery. Some of them have been attending sessions with ...
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Continuous between participant factors

for my doctorate thesis, I would like to test the effect of behavioural inhibition (continuous variable) on stress reactivity in two different groups that will be separated on their past stressful ...
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Large discrepancy between MorePower and G*Power

I am planning the required number of subjects for a 2x2 analysis (one within-subject and one between-subject) to detect a medium-sized interaction effect ($\eta_p^2$ = 0.0588). As a first estimate, I ...
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I am confused as to which nonparametric procedure I should be performing on my data

My question reads: "A computer laboratory manager was interested in whether there was a difference in functioning time for three different branded battery packs for laptop. The manager took a random ...
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Autocorrelation in a subdivided unit of analysis [closed]

Sorry if this is awkwardly worded...I'm not sure how else to describe my question. I have 4 "experiments" containing 3 "duplicates" with 28 "runs" in each. Each run is a time series of 300 seconds....
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Comparing linear mixed effects models using ANOVA - underlying assumptions

I am trying to analyze some CPUE (Catch Per Unit Effort) data for a fisheries related analysis with lme models in R. So I have total of six models that are tested in groups of two to determine the ...
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Statistical analysis, repeated measures t test or anova? Trouble with input when running any test

I've tried using google sheets/excel, but I can't figure how to run a 2 factor without repetition ANOVA (if that's the appropriate test for this data set). I think it's the way I set the spreadsheet ...
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summary of lm to compare models instead of ANOVA

What does it mean to use anova to compare models? For example, if I have two models $$ \text{model}_1 \colon y = b_0 + b_1 x_1 + b_2 x_2 $$ and $$ \text{...
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Why not remove an experimental group and do a t-Test instead of an ANOVA?

This has never been made clear to me before, so I would love some help. Lets say I have 3 experimental groups of animals (A,B,C) A is the baseline control, B is treatment x, and C is treatment y. I ...
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How we work on choosing an ideal covariate in ANCOVA (comparing covariates)

Does the scaling of the covariate matter when using ANCOVA? ex:I conduct an experiment between 2 methods A and B, example an elementary instruction and want to find out which method is more effective ...
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Simple-Effects Test for Unbalanced Mixed Design ANOVA

I am working on an Open Stats Lab activity for factorial ANOVA and have posted my analysis on GitHub. Once I have a significant interaction, how do I conduct a simple-effects test in R? The mixed ...
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Should i use a 2x2 ANOVA or a paired t test design?

I am writing a proposal answering the question does engagement in synchrony improve empathy levels in those with ASD? My sample is 1) ASD individuals receiving the synchronous intervention and 2) ASD ...
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R: One way within ANOVA output

I'm running a One Way within subject ANOVA in R as follow: testSlopeOneW=aov(Slope~Confidence+Error(Subject/Confidence),dat) Subject and Confidence are factors, ...
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Confused with Sum of squares between groups and Sum of squares between persons

I am not new to Statistics. I have studied ANOVA and its terms i.e., Sum of squares between groups and Sum f squares error etc. A few days ago I have read somewhere: Question 1. Define the following ...
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Interpret Results From ANOVA of Transformed Data

Similar questions are out there, but they do not answer my question in particular, so I decided to continue with asking mine In a simple experiment, we took different material balls of similar radius ...
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Pairwise comparisons after ANOVA with Tukey and Bonferroni methods in r

The built-in functions TukeyHSD and LSD.test from R perform pairwise comparisons. In order to maintain the type I error, the significance level $0.05$ is divided by the number of comparisons $k$. Do ...
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FIsher's LSD test is appropriate for restricted mean comparisons

Suppose that we perform two way ANOVA with interactions, with factors $A$ and $B$ with three level each $A_{1},A_{2},A_{3}$ and $B_{1},B_{2},B_{3}$. We know that Fisher's LSD test is used for ...
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Degrees of Freedom in Backward elimination

OK. I just had an exam and realized I made a mistake on a question and wanted to seek some guidance. The problem was essentially: "Use backward elimination to choose a set of predictors to predict ...
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What statistical test to use to determine significance of this data set?

For a project, I observed and timed the behaviors of a total of 39 squirrels (about 6 per day) over the course of 6 days and compared their behavior to the ambient temperature. I used a behavioral key ...
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Any 'quick' way to test which of 50 variables affects 1 dependent variable?

I've very rusty with my statistics. I know I can test each one by one. But is there a quicker test? Specifically, I have a list of 300 clients with a "contact rate" (dependent variable). If I have ...
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What steps to take after your reduced model causes unequal variance, but your full model doesn't?

I have been told that you should always check to determine which model is a better fit by comparing reduced vs full model. However I am not sure what I should do in the case that my full model(three-...
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Unsure which data to use for ANOVA test

I have determined that a one-way ANOVA test of variances will work best for my data. However, the nature of my data makes me very concerned about making any claims based on significance or not. My ...
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ANOVA with post hoc for non-normal data with unequal variance

I have 200-some variables with 25,000 observations in each of 4 categories. For each variable individually, I need to identify where we have variability between categories. Therefore, I need an ...
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Weird results in ANOVA: the three-way interaction has a pvalue of exactly 1

I am running a three way interaction, predicting 'judgment' from 'factor_1' (between subject, two levels), 'factor_2' (between subject, two levels) and factor_3 (within subject, two levels). I have ...
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What kind of statistical design would you do given the sampling distribution (in picture)?

My thesis mentor gave me samples to work with. Explanation of sampling pattern: There are three samples per field (plot) to which are conjoined three samples from an adjacent plot. The plot differ ...
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Repeated measures ANOVA sample size calculation using R

I'm trying to conduct a sample size calculation for a repeated measures ANOVA. The study will involve taking 10 measurements from participants. Prior to each measurement, participants will be ...
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ANOVA Test Necessity

I have a question which may seem very simple to someone with more experience in statistics. I have performed a two-factor ANOVA test, without replication, in order to test if there is a significant ...
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ANOVA with dependent means?

I want to perform an ANOVA test on where hospital equipment is located within a hospital on different days of the week and months of the year. My dependent variable is the proportion of equipment in ...
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Can someone explain what the difference is in the p value of the summary output and emmeans (pairwise, least square means)?

I have a model: m_ramet<-glmer(ramets_net ~ salt * typhagroup + ramets_start + (1|site),data=morphdata, family="poisson"(link="log")) and am ...
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Appropriate hypothesis contrast between 4 different car brands (fuel consumption)

Is there any significant difference between the manufacturers regarding fuel consumption? I typically use t.test as: ...
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68 views

Singular fit (or not) for 2 seamingly identical mixed effect models and questioning the validity of a random intercept

This is a follow up question to this first question : First question I have two seemingly identically structured datsets ...
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Misleading two-way ANOVA table interpretation

How can the hypothetical cases below (if possible) be explained? Assuming randomness, normality, homoscedasticity, etc 1-Overall effect (Fbetween) is significant Individual factors are NOT ...
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How interpret the results of nested ANOVA?

I have nested ANOVA with three variables (impact -> amount -> item). amount is nested within ...
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Why is the sum of squares within treatments referred to as the sum of squares due to error? (single factor ANOVA)

compared to the sum of squares among treatments, why is within treatments variation attributed exclusively to error?