All Questions
Tagged with heteroscedasticity anova
130 questions
0
votes
1
answer
48
views
Bradley's liberal criterion
I'm reading an article where the authors utilized Bradley's liberal criterion to estimate the robustness of the F statistic in the context of post hoc tests.
The problem here is that they said the ...
0
votes
0
answers
50
views
Two Way Anova with Heteroscedasticity
I'm trying to run a two way anova test but the homoscedasticity condition is not met. My analysis is not balanced and I have over 3000 observations in my sample. Is it okay to proceed even if the ...
- 155
1
vote
0
answers
32
views
Does "residualising" out the effect of a covariate on the response variable achieve similar results to including the covariate as a predictor?
Sorry - the question itself is wordy!
I am running a Welch ANOVA, but want to account for the effects of a covariate on this Welch ANOVA. I am unaware of any ways that I could conduct a Welch ANCOVA.
...
- 41
3
votes
1
answer
256
views
Which Levene statistic do I report?
I am writing a paper comparing quantitative values across $5$ groups. I have performed an ANOVA in SPSS 29 and have requested from the software the Levene statistic to judge if there is homogeneity in ...
- 503
0
votes
0
answers
40
views
How to visually check for homoscedasticity? [duplicate]
I want to know what to look for in a boxplot, when we want to check for homogeneity of variances among groups, which is an assumption in ANOVA.
I used this codes to get a boxplot:
'''boxplot(log(...
- 73
2
votes
1
answer
61
views
Anova model assumptions. How to go by?
I have a data frame that contains a continuous response variable measured on different species, at different elevation and month of sampling as explanatory variables. I want to analyze how the ...
- 73
1
vote
1
answer
112
views
Transformations to meet heteroscedasticity
I have a dataset containing angles. They represent the bending angle that a seedling makes to go toward light. I have two factors: treatment and genotype, so I use a two way ANOVA. However, the ...
0
votes
0
answers
30
views
I am using Stata to perform my statistics for a paper. What should I do if a sample is normally distributed but don't have equal variances? [duplicate]
I am using Stata for my analysis. I am analysing a numerical variable over a categorical one (with 3 groups). After confirming they are normally distributed, I did a one way ANOVA test. But Bartlett's ...
0
votes
1
answer
108
views
How should I proceed with a one-way ANOVA if homogeneity of variance is violated, I have unequal sample sizes, and I want to control for covariates?
I'm using SPSS. I have a multi-level categorical IV and a few continuous DV's.
My main analysis goals are to test the effect of the IV on the DV, and then to follow-up with pairwise comparisons of ...
0
votes
1
answer
73
views
Two-way ANOVA but normality and homogeneity violated
I have a 2x3 between-subjects design.
I want to run two-way ANOVA but have no normality and no homogeneity. I have 3 variables and 103 observations in total.
Factor 1 - attentional bias (CFT): G0 n....
5
votes
2
answers
443
views
How to compare more than two groups of continuous, not-normally distributed values?
I'm currently analyzing the age variable in a dataset of all italian phyisicians (~470,000 obs) and I'm trying to check if age is significantly different between three groups defined by another ...
- 151
4
votes
3
answers
3k
views
Check the homogeneity of variance assumption by residuals against fitted values
I am studying this source about One-Way ANOVA Test in R. We know that ANOVA test assumes that the data is normally distributed and the variance across groups are homogeneous. In the source the claim ...
- 389
1
vote
1
answer
64
views
Testing assumptions for repeated measures ANOVA
I was wondering how to assess residual normality of a repeated measures ANOVA. In some threads, users refer to Venables and Ripley: Residuals in multistratum analyses: Projections and recommend to ...
- 433
0
votes
0
answers
65
views
How can I transform my data to achieve homogeneity for a factorial mixed ANOVA?
I'm fairly new to statistics (I'm doing it for my bachelor thesis). I want to do a factorial mixed ANOVA in Jamovi, but not all of my data is homogenous (15 out of 126 measurements are not homogenous)....
- 1
0
votes
1
answer
273
views
Why is there an apparently large difference between Bartlett and Levene's test in this problem?
When running tests for homoscedasticity, using R gave the following results:
...
- 11
1
vote
1
answer
509
views
Analysis of variance vs. homoscedasticity assumption
If the assumption of homogeneity of variances is met,
how could the variances be different among groups in ANOVA
(the analysis dealing with between/within variability) ?
That is for me, ANOVA is ...
- 1,831
3
votes
2
answers
415
views
Anova with unequal variances via regression modeling
I would like to fit a one-way between-subject anova that assumes unequal variances between groups.
Reproducible example:
...
- 613
1
vote
0
answers
51
views
State-of-the-art nonparametric $k$-way ANOVA allowing heteroscedasticity
QUESTION: Can you recommend a nonparametric version of a multiway ANOVA that is also robust in the absence of homogeneity of variances? So, this is what I am looking for:
(1) Nonparametric ANOVA (no ...
- 789
-2
votes
1
answer
49
views
How to tell if data has homgenous variance? [closed]
I am checking the assumptions of ANOVA model and I want to see if the condition of homogeneity of variances is met in my model. I made such a plot, but I am not sure what to look at here and what ...
- 27
2
votes
1
answer
1k
views
Equal Variance vs. unequal Variance for comparing Groups
I am a little bit confused about equal and unequal variances. I understand the definition and mathematics behind it, yet I don't know, for the purpose of my research, how to appropriately test that.
...
- 23
3
votes
2
answers
753
views
is there any non parametric Welch's ANOVA?
I need to test for differences between non-normally distributed and heteroscedastic data.
I know that I can use the Kruskal-Wallis test to assess significant differences between groups but one ...
- 151
0
votes
0
answers
33
views
Which design one-way ANOVA or 2-way ANOVA using SPSS?
I have 2 drugs A & B with different 6 concentrations and for both drugs, at a specific concentration, the result is recorded (3 replicas),
so I am confused.
I have tried 2-way ...
- 1
0
votes
0
answers
60
views
Ensuring that sequence of repeated trials does not bias result
Imagine the following experimental design:
You have four conditions, A,B,C and D, regarding an online platform. Conditions A,B,C have a different feature enabled that you want to compare and D has ...
- 1
0
votes
0
answers
42
views
ANOVA, does "equal population variances" mean the same as "a single population"?
In ANOVA the assumption is made that the population variances of the different groups are the same. Assuming $H_0$ is correct, all population means are also the same. In this case, would it not be ...
- 311
0
votes
1
answer
164
views
Assumption of Homogeneity of variance [duplicate]
Why is assumption of Homogeneity of variance required. What are the problems if they are not satisfied
- 11
0
votes
0
answers
10
views
which test to do first? [duplicate]
I have a dataset that has 4 Columns as x axis. I want to check the data for:
Autocorrelation,
Multicolinearity,
Heteroscedasticity and
Normality,
In what order should ı perform the tests?
And ıf my ...
- 11
1
vote
0
answers
276
views
Does HC3 correction for unequal variances work in mixed ANOVA?
Since equal variances are necessary for any ANOVA that contains between-subject factors – regardless of whether it also contains within-subject factors – all such cases need correction (or alternative,...
- 234
5
votes
1
answer
840
views
Alternative to Mixed ANOVA without homogeneity of variances
As is tradition on these posts, I should say I'm relatively new to statistical analysis at this level so if I don't provide enough info off the bat bear with me.
So I've conducted an experiment ...
0
votes
0
answers
270
views
When distributions are non normal and heteroscedastic, is it preferred to use ordinal logistic regression or permutation tests?
I am currently conducting statistical tests on my two independent samples (both with more than 1500 entries each). The sample sizes are no equal. My response variables are interval as well as quasi ...
- 13
7
votes
1
answer
2k
views
Is there ever a statistical reason NOT to use Satterthwaite's method to account for unequal variances?
Two related questions:
1) From what I've read, using Satterthwaite degrees of freedom does not assume equal variances, which allows it to be used on datasets that would be inappropriate for, say, a ...
- 229
3
votes
2
answers
8k
views
Analysis of variance for nonnormal data with unequal variance
I would like to ask whether it is possible to perform an analysis of variance on data that is not normally distributed and has unequal variance, but I have large enough sample size.
I have read that ...
- 31
1
vote
1
answer
442
views
Different ANOVAs by subgroup
I am analysing data which I generated using a simulation model. Due to the stochasticity of the model, the output is also stochastic. I have several dependent variables (let's say X and Y) and vary ...
- 11
3
votes
2
answers
433
views
Model selection for Mixed Effects Regression - Correcting heteroscedasticity
My experiment consist on measuring the root mean squared error (RMSE) between a path and what the participant produces. To produce the trace each participant experiences 3 feedbacks (1st factor - ...
- 60
3
votes
0
answers
1k
views
Test for non-normal data with homogeneity of variance
I'm new to the platform and would like the following question to be answered:
I have performed a latent class cluster analysis with 28 variables and 9000 observations, for which I am currently ...
- 41
4
votes
1
answer
760
views
Unequal variance in randomized experiments to compare treatment with control?
Consider a randomized experiment to compare (one or more) treatment(s) with a control. Since groups are defined by random assignment, we should expect equal variances for a null-experiment (that is, ...
- 82.8k
1
vote
2
answers
2k
views
Help interpreting residual vs fitted plot and normality (ANOVA on R)
I'm carrying out a statistical analysis on R using ANOVA and am not sure if the data meets the assumptions of normality of residuals or homogeneity of variance.
My data :
And my plots:
Any help is ...
- 31
3
votes
1
answer
520
views
Is one-way ANOVA robust to violations of homoscedasticity?
I read here that if group sizes are equal, ANOVA is robust against the violation of the assumptions of normality and homoscedasticity.
I am wondering if this is the case, and if so why?
- 133
3
votes
1
answer
957
views
Analysis of variance with not normally distributed residuals : how important is normality?
I am using gls and anova to analyse my data. I use gls to aply weights. I have one factor (tree genotype) and I analyse its influence on soil content.
Here is an exemple of my data with one variable (...
2
votes
1
answer
303
views
What to do when Breusch-Pagan shows heteroscedasticity but plot looks it might not?
So I'm trying to run a Least-Squares Means with a covariate. However when I run Breusch-Pagan test it shows heteroscedasticity even after either tukey or log2 transformation, however the plots seem ...
- 331
1
vote
0
answers
23
views
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 ...
- 33
1
vote
1
answer
45
views
why homogeneity test is used for ANOVA not for t test?
Why the homogeneity test must be curried out for ANOVA test but not for t-test when sample size is more than 30 ?
- 41
3
votes
0
answers
1k
views
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 ...
- 31
1
vote
0
answers
268
views
What to do when there is heteroskedasticity in an ANCOVA model?
What to do when there is heteroskedasticity in an ANCOVA model?
Is there a correction similar to Welch ANOVA?
Or is better to use a OLS regression model?
Should we try to solve heteroskedasticity by ...
- 561
2
votes
1
answer
4k
views
Assumption of homoscedasticity/equal variance violated in a 2-way ANOVA
I'm analyzing results from an experiment where 56 samples were tested for a specific response to electrical stimulation. Electrical stimulation was done at 2 different stimulation frequencies, and at ...
- 55
1
vote
0
answers
262
views
Homoscedasticity test for repeated measures ANOVA, SPSS
My experiment has three treatments, looking at different measures of animal behaviour in response to each treatment.
Firstly, is testing for homoscedasticity for a ...
- 11
2
votes
1
answer
495
views
How is homogeneity of variances in residuals a requirement for ANOVA, when ANOVA is a test that involves analysis of variance?
I know this is a basic question about ANOVA, but I don't understand why it's important to have homogeneity of variance across different groups within a factor, when you are 'analyzing the variance' to ...
- 183
0
votes
0
answers
272
views
Equal variances not assumed in Three-way ANOVA
I'm working on my thesis and I've entered the data of my survey in SPSS. It's a 2x2x2 between subjects experiment and I'm researching whether sustainability of the product (yes/no), sustainability of ...
8
votes
3
answers
2k
views
What is the worst that can happen when the homoscedasticity assumption is violated in ANOVA?
This is a follow-up question I have after reviewing this post: Difference in means statistical test for non-normal, heteroscedastic data?
To be clear, I am asking from a pragmatic perspective (not to ...
- 6,064
6
votes
1
answer
1k
views
Difference in means statistical test for non-normal, heteroscedastic data?
Suppose I have a data set with three or more groups. After some exploratory data analysis, I find that
The groups do not come from a normal distribution
the variances within the groups are not equal,...
0
votes
2
answers
1k
views
Satisfies Assumption of Homoscedasticity?
I'm in the process of conducting a multiple regression model and have created the following test to see the variance of the residuals in my model. That is the graph for the original data and has had ...
- 47