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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low sample size experimental design, t-test vs one way ANOVA

I'm designing a biological experiment wherein the sample size is very limited, as each sample is very hard to get. Moreover, I need to have 4 independent groups, each receiving a different treatment. ...
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Appropriate statistical test to compare groups containing discrete data

I need to compare more than 2 groups, each containing discrete data (more specifically, integer numbers between 1 and 9). Shapiro-Wilk tests come back as significant for most groups, meaning the data ...
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showing significance of gender differences in control vs treatment groups

I have 4 groups with independent samples : Female Control Female Treatment Male Control Male Treatment When I compare Control to Treatment within the same sex, I find that Female Control to Female ...
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Should I perform a Post Hoc analysis if I get no significant interaction in two way anova?

Hello all! I am performing a two-way ANOVA for an experiment I am doing but I reached a concern. I saw no significant interaction effect, still, I performed a post hoc TUKEY test and got significance ...
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Parametric and non-parametric statistical test for between groups differences in means with "repeated measures"

I am trying to understand the appropriate statistical tests for the following experiment: I have 3 different groups consisting of 5 individuals per group (each individual is a member of only a single ...
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Linear regression assumptions violated

I have an independent variable hours/day sitting and a dependent variable test scores, I think all of the assumptions of linear regression are violated, as in the pictures that I added So I did one ...
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Best method for this study design

I have 7 independent variables age (continuous variable), body mass index (continuous variable), gender (catagorial variable), department (catagorial variable), hours/day on computer (catagorial ...
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I do not know how to explain how my P value and my F stat do not coincide [duplicate]

I am having trouble with an ANOVA test. I cannot figure out how to explain that I would not reject the null with a P value >.05 but my F stat came out larger than the F crit. Any ideas? I am ...
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Several one way anovas vs factorial anova

Is running several separate one-way anovas instead of factorial anova or two way anova have a big influence on p-value? If i run separate anovas will I get completely wrong results? I have 7 ...
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Older adults verses Younger adults - RM ANOVA non sig interaction

I am running a 2x4 ANOVA (between: old verses young adults), (within: reward 4 levels). In the overall model I have a significant main effect of reward, and a non significant interaction. I have no ...
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Anova table for linear model, $3$ treatment groups with model $Y_i = 4+6 I_{1,i}-1 I_{2,i}$

Anova table for linear model, $3$ treatment groups with model $Y_i = 4+6 I_{1,i}-1 I_{2,i}$ where $4=B_0 = \bar Y_1$, $B_0+B_1=4+6=\bar Y_2, B_2=\bar Y_3$ and each group has a $5$ patients. The ...
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Compare mean of subsamples between groups

I am going to collect quantitative data for two groups that I would like to compare. I have done a two sample t-test on some preliminary data and found a significant difference, but I don't think that ...
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In ANOVA, how can we link difference in sample means to ratio between MS between and MS within? [duplicate]

The logic of ANOVA is as follows: We want to figure out how much of the total variance comes from between the treatments and within the treatments. Hence, we use: F = MS_between/MS_within The larger ...
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2x2 Repeated measures ANOVA gives DIFFERENT result in R and SPSS? (Same type of sums/data/analysis) Anyone know why?

Reposting this because I fixed the formatting to see if someone can actually provide a solution for this problem. I have a study design in which I am carrying out a 2x2 repeated measures ANOVA in ...
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How to test both main effects and interactions using continuous variables?

My design has three continuous variables (duration 1-3), one ordinal variable (level), age and gender as independent variables. Dependent variables are six different questionnaire results. I want to ...
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Correctly specify nested error structure for a split-plot ANOVA

I would like to check we are thinking about an approriate model structure for an experiment we have run, and whether I have specified this correctly in R. I have data from an experiment using plants ...
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Which test when I have paired observations in more than two treatments?

I have doubts on which test I should use when I have measurements on the same individuals under more than 2 different conditions. I have a sample of rats, on which was measured the effect of different ...
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Separate anovas or 7 way manova?

I have 7 independent variables and two dependent variables which I think I should run 7 way manova, but this method is to complicated to compute, is running separate anovas for each dependent variable ...
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Spread of species and site scores in R (vegan) DCA ordination

I have performed a Detrended Correspondence Analysis on social survey answers, aiming to see the spread of answers to 25 interview questions and how they related to the three farmer types (n =45) we ...
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Which method is best?

I have an independent variable which is BMI and catagorized into 1- under weight 2- normal weight 3- over weight 4- obese Sample size is 100 The dependent variable for group 1,2 and 3 is not normally ...
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How to convert my output into a suitable table for ANOVA or Kruskwallis testing on SPSS?

Let's say I have asked an individual to classify images according to 3 fruits that he sees : apple, banana and kiwi. Then, I want to assess whether there are significant differences between the ...
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Obtain Multiple Regression coefficients from Partial Correlation Coefficients and ANOVA table

I know, that results from multiple linear regression, partial correlation analysis and ANOVA are tightly related to each other. The answers to this and this question indicate that the results may be &...
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What is the appropriate way to statistically analyse diversity indexes?

I have been working with a soil-derived viral metagenomic data set and am looking for advice on the appropriate statistical approach to the results. I have 2 different sample areas. Within both areas ...
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Three-way manova or separate anovas?

I have three independent catagorial variables and two dependent continuous scale variables, so I want to compare means across these three independent catagorial variables. I think here the best choice ...
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Appropriate analysis: 1st independent variable has one value for each participant, 2nd has multiple levels

I need a suggestion about the appropriate analyisis for my data set. I have 2 independent variables. One of them is the proportion of the time spent in a specific activity. Each participant will have ...
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Pros and cons: Splitting a single dummy variable into multiple and fit seperately

I was discussing dummy coding with a colleague. They wanted to compute a series of combinations from the levels of a three-leveled categorical variable (A vs B+C; B vs A+C; C vs A+B) but as it's not ...
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Is this the correct test to perform?

In my research I have 4 independent variables which are gender, BMI, department, and hours spent on computer and two dependent variables which are test scores for two different tests (SSS) and (FSS). ...
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2-way ANOVA on grouped Data, question about significances after multiple comparison

so I am currently analyzing data from my experiments. As seen on the pictures, I have 2 different cell populations (cDC2 and DC3) to analyze, with various different stimulations (depicted as R848+...
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Statistically comparing supervised text classifiers

I currently have 4 supervised text classifiers, namely: Naive Bayes, Semi Naive Bayes, Bernoulli Naive Bayes, and SVM. As a performance metric, I am currently using the F1 score. I also wish to deduce ...
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What test is appropriate? [duplicate]

can I do welch one way anova to compare mean between the following three groups Group 1 has 83 observations Group 2 has 15 observations Group 3 has only 2 observations And in group 3 the variance is 0 ...
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2 votes
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Which test should be performed if variance is 0?

Hello I have 100 students who answered the question, time spent sitting and I divided it into three groups: Group 1: (6-9) hours Group 2: (10-13) hours Group 3: (14-17) hours Also the students ...
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On what conditions of a 2x2 ANOVA is a post-hoc test necessary?

If the point of a post-hoc test is to determine where exactly the variance originates from, then does an ANOVA 2x2 results table, where all of the sources of variation between different groups are ...
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SPSS 3x9 (3x3x3) Study Design issues

I am currently conducting a supplement experimental trial that is analysing Power Output (Dependant variable) against three independent time points (Week 0, 2 & 3). Each time point is subject to ...
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Factor effects model vs. dummy coding model in linear regression [duplicate]

I did some analysis that showed that one of my two factors was significant when I modeled it as a dummy coded variable (each of my two predictor variables has just two levels, and so the "on"...
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Do Eta Squared and Partial Eta Squared Coincide in One-Way Repeated-Measures ANOVA?

In one-way anova, do eta squared and partial eta squared always coincide, both in between- and within-subjects designs, i.e. both in independent and repeated measures designs? I have been discussing ...
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Differences between factor effects model and dummy coding model

I have a set of data and see that when I create a factor effects model rather than a dummy coding model, I get different results. In my model, tbStatus and treatment each has two factor levels, with ...
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Reporting multiple one-way ANOVAs concisely

I am writing a report on my findings. I have used an ANOVA test on 15 different dependent variables. The dependent variables are execution times of some processes. I considered the variables ...
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Clarification about ANOVA assumption of normality [duplicate]

A few quick definitions: An error is the difference between an observed value and the "true" value A residual is the difference between an observed value and the "predicted" ...
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Test to obtain p-value of the random effect in mixed models

I would like to obtain the p-value of the random effect for a simple linear mixed effect model. To be more precise, my model is: $$\mathbf{y}=\mathbf{X}\boldsymbol{\beta}+\mathbf{Z}\mathbf{u}+\...
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Why is the Mean Square Between (MSB) used in 1-way ANOVA instead of total variance?

I'm having a hard time parsing the logic behind the formulas in the 1-way ANOVA. I'll first establish what I understand so far which will lead into my question. The objective of a 1-way ANOVA is to ...
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2*2 repeated measures ANOVA with an unbalanced number of observations

Sorry for this very basic question. I've trawled through previous pages and cannot quite find a case that corresponds to our situation. 320 individuals rated two types of films. The rating was ...
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p-value adjustment/correction on main effects & interactions (F-tests / ANOVA)

I performed 8 ANOVAs on the same subjects with different dependent variables. We tested the significance of each term & interactions using F-tests (ANOVA). A reviewer asks us if we have applied ...
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What's the correct tool to compare means between very small groups?

I'm not really used to VERY small samples, so I'm wondering what to do in the following situation: I have 3 groups, A, B and C. Each of them consists of 3 observations. I want to test whether there is ...
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Calculating $Cov\left(\overline{Y}_j,\:\overline{Y}\right)$ for a basic one-way model

Consider the basic one-way model: I want to show that $Cov\left(\overline{Y}_j,\:\overline{Y}\right)=\frac{\sigma ^2}{na}$. I derived the following expected values: $$E\left(\overline{Y}_j\right)=\mu ...
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How to Set up a Mixed Effects Model with 2 Between Subject and 1 Within Subject Factors

just trying to make sure that I'm setting all of this up correctly for a mixed-model ANOVA because I keep getting ...
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Problem with sample size: total number with mean or individual cohorts with mean?

I have a climbing assay where I use cohorts of multiple flies and calculate a performance index based on their climbing speed. I do this 15 times and then take a mean for the cohort. This has been ...
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Unbalanced groups in repeated measures anova

I am analysing metabolomics data (~1,000 measurements) across 30 samples from 10 subjects. The samples are from 2 treatments groups of 5 subjects from whom 3 muscle samples were taken from 3 locations ...
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SPSS and Research Design/Analysis HELP

For my Major Research Project, I am investigating: Online versus Virtual Learning Environments - to determine the effect of student engagement on levels of presence when comparing these two ...
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2 votes
1 answer
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What is the best way to test a group of interaction effects in a GLM?

I have a binary outcome Y and predictors a, b, c, and d. I have a logistic regression model which includes all the predictors, plus all the interactions between all the predictors. What is the right ...
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Anova and mixed effect models (lm4 / nlme) return complete different effects

As a continuation of a previous topic, I would like to address a similar experience. Subjects completed an experiment in which their electrodermal activity was recorded. For each subject there are 72 ...
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