# Tagged Questions

ANOVA stands for ANalysis Of VAriance, a statistical model and set of procedures for comparing the means of groups of related data. Generally the independent variables in an ANOVA analysis are categorical, not continuous.

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### Statistical Tests for comparing groups

I am a biologist and I have developed an algorithm that has the ability to identify and quantify fluorescent objects within the nucleus of a cell when imaged in a fixed state under a microscope. The ...
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### Running a Tukey's test on a repeated measures ANOVA in R

I've come across several posts dealing with post hoc tests of Repeated Measurs ANOVA. I came up with the below code in R to attempt this, but considering some of the posts on this subject I wanted to ...
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### Repeated ANOVA unbalanced data

I did experiment on one group of rats, the group was tested during 8 days, this is the first stage. The same group was also tested again but this time the test phase was 7 days. I tried to do my ...
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### Unequal Sample Sizes for Two-way Repeated Measures

I have 3 different treatments with the observations of 6 different repetitions. However, all these different treatments (groups) have different numbers of patients. The first group has 26 patients, ...
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### How to calculate type II error between glm fits in R?

I'm using a GLM with logistic link function to try to predict Y (0 or 1) as a function of a ton of predictor variables (A, B, C, etc.). Some of the predictor variables (A*, B*, C*, etc.) have been ...
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### Question about Tukey post-hoc ANOVA test results

I have used a Tukey post-hoc test after seeing that the ANOVA test indicated some significant differences between my groups (A,B,C,D). I am somewhat confused about the results. Why, for example, is ...
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### What are the limitations of ANOVA vis a vis multiple regrssion analysis"

It seems that multiple regression is a better way to do analysis while ANOVA simply gives t-value. The latter does not indicate magnitude of effect and regression analysis indicates both the t-value ...
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### Running several one-way ANOVA tests on different groups of the same data without inflating type I error

I have 2 categorical independent variables (industry & location) and 1 continuous dependent variable (performance metrics). I need to find significantly different industries by mean performance ...
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### Help with unbalanced 2-factor ANOVA in R

I have a dataset that is unbalanced, where I have a response variable (age) and 2 factors (factor 1 = gender; 2 levels = m and ...
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### Compare means - heterogeneous variance, non-normal

I would like to perform some basic means comparisons (3 conditions, balanced, n = 21 for a total of 63 observations). The main dependent variable is total task completion time, i.e., the experimental ...
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### Alpha adjustment for main and interaction effects in multiple factorial ANOVAs

let's say that I performed 10 2x2 factorial ANOVAs. In total I get 30 effects (two main effects and one interaction for each ANOVA). When adjusting the alpha level for multiple comparisons, should I ...
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### Mathematical Explanations behind ANOVA

I was wondering: could someone could direct me to papers (preferably) or textbooks that give strong explanations of the mathematical background behind ANOVA?
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### Independence of numerator and denominator connected to independence of obs?

I was wondering whether the independence of the numerator and the denominator in the ANOVA F-statistic relates to the independence of observations and how?
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### ANOVA repeated measurements

I am a master's student, and I need your help. I did experiment on one group of rats, the group was tested during 8 days, this is the first stage. The same group was also tested again but this time ...
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### Repeated measures ANOVA with unbalanced data [duplicate]

I am a master's student, and I need your help. I did experiment on one group of rats, the group was tested during 8 days, this is the first stage. The same group was also tested again but this time ...
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### Regression or Manova?

I have the following problem: I have one manipulated IV (degree of co-creation) based on three surveys "no" "low" and "high" degrees of co-creation. Furthermore I have 4 DV (Purchase intention, ...
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### eta-squared by hand

This code outputs the eta-squared from an ANOVA: ...
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### How do you “control” for a factor/variable?

To my understanding, "Control" can have two meanings in statistics. Control group: In an experiment, no treatment is given to the member of the control group. Ex: Placebo vs Drug: You give drugs to ...
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### Analyzing differences in preference for proportional data

We have conducted an experiment using a two-alternative forced-choice task where listeners must indicate whether they prefer the sound quality of an auditory stimulus in interval A or interval B. ...
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### Difference between MANOVA and two-way ANOVA

I have read the articles of both of these statistical methods on wikipedia, and as far as I can tell they are used in the same cases. I could not tell in how far they work the same way, since the ...
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### Interpretation of p-value for one-way ANOVA and two-way ANOVA

We are currently handling some results and performing some ANOVA tests on human search performance in virtual environments using different sound systems for audio rendering. We measure the time it ...
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### How to deal with unbalanced group sizes in mixed design analysis?

I have 2 x 2 x 2 mixed design with two between subject factors (sex, organizer) and one within subjects factor (task). The group sizes of the 'sex'-factor is unequal. When I perform a factorial ...
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### Substitution test for ANOVA?

I am working on biological dataset. Around 20000 genes of each sample are comparing with the same ones in another group in order to find significantly differentially expressed genes. I am comparing 3 ...
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### How to analyze within and between observer error, with count data?

I have a data set that consists of counts of striae (lines) on fish teeth. I want to assess within observer and between observer error for my data, and compare values to published counts of the same ...
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### ANOVA with very uneven sample sizes— Can fit be improved through reference to a more complete dataset?

I am analyzing a set of costs for contractor services for a particular city. These data have been extremely difficult to collect due the difficulty of contacting contractors and reluctance of ...
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### Compare variance and point statistics in a 3 way group

I need some help on this analysis. I have 3 groups of individuals, different the level and kind of physical activity. For each individual I have the heart rate, taken every minute for ~24h. (each ...
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### Why isn't the Anova() function in the Car package returning an F statistic?

I ran a simple psychology experiment that included 4 conditions, each containing 8 blocks of training. There were different participants in each condition. Hence, condition and block and subject and ...
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### What is a non parametric equivalent test for two-way anova that can include interactions

Hi I am trying to find the non-parametric equivalent of a two-way ANOVA (3x4 design) which is capable of including interactions. From my reading in Zar 1984 "Biostatistical analysis" this is possible ...
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### Post-hoc test in two-way ANOVA

I am doing a two-way independent ANOVA using type of organisational change (5 levels) and job level (7 levels) within the organisation as the factors (in SPSS). I followed Andy Field's procedure ...
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### Correction for multiple comparisons

I have a 2x3x4 repeated measured anova. I have a significant 3-way interaction, and I want to make sure that I am using the correct post hoc comparisons and not violating any key statistics theory. I ...
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### How to check the assumption of equal error variance might be violated?

I want use this box plot to check it. Thank you
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### How can I write up Tukey HSD findings?

the result of SPSS is uploaded in image form. This is exactly a part of my HW. And it make me confused for like 1 hour. Use the Tukey HSD procedure in SPSS to determine which levels of the factor ...
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### 1 control group vs. 2 treatments: one ANOVA or two t-tests? (3 or more groups = ANOVA but explanation needed)

I have 3 groups, one control group and two treatment groups that have nothing to do with each other. I just want to see if any of those 2 treatment are different from the control group. Textbooks ...
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### How can I calculate F critical value in ANOVA method knowing df1, df2 and alpha?

I'm very new to the statistic methods but at the beginning of my wonderful math-journey I found some problems. Two days ago I got to know the ANOVA method. I'm kind of familiar with it today, but ...
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### Comparing two F-test statistics

I have two groups A and B, each of which consists of 5 samples. Each sample is described in a vector of length (>1000) of continuous numeric values (characteristics). I want to test if the sample in ...
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### Interpreting multivariate tests in repeated measures

I have a within subjects design with 4 DVs and I ran a repeated measures analysis on SPSS. My DV is a physiological measurement and is not expected to be linear. My multivariate Wilks lambda is ...
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### Null hypothesis of t-test and ANOVA

I've recently started to brush up my statistics, and have begun doing so with two of the most often used statistical tools in my field: the t-test and ANOVA. Reading up on popular information sources ...
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### Repeated measurements with missing values

The data is measured in two biological replicates with two technical replicates, each. Each variable might be detected only in one or more replicates, in the others it is considered missing at ...
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### F-test for equality of regression coefficients

I have been trying to look for a reference on the theory behind using the F-test to test for the equality of regression coefficients. The closest I could find is this, which is for general linear ...
373 views

### Mixed linear model with repeated measures in SPSS

I'm trying to run a mixed linear model analysis with SPSS. When I try to run the analysis, SPSS gives the following error message: ...
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### Hierarchical variable: checking whether two subgroups have to be distinguished or can be pooled together

I am doing a study to analyze the effects of knocking out a particular gene on a certain behaviour in flies. After a log transformation, my observations have a normal distribution so I'm going to do a ...
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### Evaluating features and similarity measures

I am currently developing a classificator, which is supposed to classify into a number of classes. For this purpose I am designing some features and similarity measures which I might use for a later ...
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### Mutual Information vs ANOVA

In the context of analysing dependencies between a continuous and categorical variables, what is the difference between mutual information and an ANOVA test with post hoc analysis? I'm aware that ...
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### Adjusting P-values in ANOVA

I am working with an experiment on several genes (#41350) based on two factors: Lcells (levels: "pos", ...
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### Repeated measures ANOVA within and between factors

I have conducted repeated measures ANOVA, with 2 factors: One within factor (time, pre-post intervention) and one between factor (...
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### How to evaluate Likert scale data changes over multiple surveys of the same group?

I have five surveys of the same group of students over a semester. Each survey uses a 5-point Likert scale. The first and last survey contain some questions dealing with the beginning and end of the ...
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### 2x3 ANOVA interaction no longer significant after including a covariate?

My experiment had a 2x3 design with one covariate. If I analyse the results using an ANOVA, I get a strongly significant interaction between the two main factors (p<.001). If I add the covariate ...
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### What statistical test should I use for this situation?

I've got three groups A,B,C. Each has a different number of records and I have calculated the mean for each group. Now I want to know if these means are equal or not? What statistical test should I be ...