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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Repeated measures with time varying covariates in R

On this page (Model 5, http://www.ats.ucla.edu/stat/spss/faq/repeat_covar.htm), there is a description of how to carry out this type of analysis using SPSS. Does anyone know how to do the same thing ...
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10 views

Calculating sample size of a mixed ANOVA in R (2 between, 1 within variable)?

I'm searching for a built-in function in R for calculating the required sample size (given certain power, alpha,..) of a mixed ANOVA (2 between, 1 within variable, 2x2x2 design). Does this function ...
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21 views

How to analyse a factor experiment with feature extraction, clustering and classification algorithms as factors?

Currently I am doing my final project, which consists of designing an experiment to test several combinations of algorithms on a dataset, such as feature extraction, clustering, classifiers and ...
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how to determine whether the results in anova is significant or not by seeing the Critical difference and Sem value?

How to determine whether the results in 3 factor anova is significant or not by seeing the Critical difference(CD) and Sem value?
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2answers
236 views

Dealing with Heteroscedasticity in ANOVA

I need to perform an ANOVA on percentages data. I have 3 factors: TREATMENT, SAMPLE and DaysAfterTreatment (DAT). Treatment has 3 levels: Control, A, B. SAMPLE has 2 levels: SampleA, SampleB. DAT has ...
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SPSS one way ANOVA

I'm using SPSS version 20 in the statistical analysis of my study. It's a case-control study, within the cases there are three polymorphisms (TT, Tt, tt) and their correspondent vitamin D level. I ...
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22 views

ANOVA result with insignificant factors

I'm having difficulty interpreting the result I get from ANOVA. Specifically, if some of the factors I put into the model have an insignificant impact (p-value > 0.05) on the output, does it mean I ...
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8 views

Why does aov consider a 3x3 factorial design unbalanced?

I have a two factor, bot at 3 levels with all factor levels, and with 5 replicates for each. This is a standard 3^2 factorial design, and yet aov gives the message "Estimated effects may be ...
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11 views

Using ANOVA to reduce number of variables

I am interested in using a machine learning technique (kriging) to model a function, based on a large number of variables. The large number of variables are causing overfitting problems, and I would ...
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8 views

How do I calculate Fisher's LSD Familywise Error Rate?

I'm trying to compute Fisher's LSD Familywise Error Rate for an ANOVA using 6 treatments and an alpha level of .05. Since there are 6 treatments, there are a total of 15 pairwise comparisons, so I ...
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13 views

Grouping variables into clusters before running ANOVA [closed]

My apologies for this novice question, but I am interested in transforming variables into another variable before running an ANOVA with a nominal variable against the transformed variable. ...
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12 views

What does the matlab function anova(mdl) do?

My data have one response and several predictors. These predictors are continous, not categorical. After regression, I wish to decompose the total ss on each predictor. With regard to this, I have ...
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Calculate sum squares within treatment

I have a group of subjects treated with a drug formulation and a parameter is measured. The next week (period 2) same group of subjects is treated with the same drug formulation and the same parameter ...
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24 views

how to test for significant preference with two variables with different number of outcomes?

In a random choice trial with two parameters (color and location), I want to test whether a choice is influenced / driven by one other factor or the other, or whether they are independent. In detail: ...
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1answer
43 views

Modeling within subjects

I am having a bit of a statistics problem, and thought I would throw it to the internet before I bash my head in. Participants were shown stimuli and asked a question while EEG was recorded. The ...
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2answers
112 views

What really happens when we transform the data using $f(x) = \sin(\sqrt{x})$?

I need to perform a two-way ANOVA on my data ($Y$: sleeping hours). My data is quite normal $p$-value = $0.07$ with Shapiro-Wilk test but when I run the normality test for my residual, $p$-value is ...
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1answer
66 views

In a two-way ANOVA, how can the F-statistic for one factor have a central distribution if the null is false for the other factor?

Consider the two factor additive ANOVA model $$\begin{align} X_{ij} &=\mu_{ij}+e_{ij} \\ \mu_{ij}&=\mu+\alpha_i+\beta_j \end{align}$$ where as usual $\sum_{i=1}^a \alpha_i=0$ and ...
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1answer
54 views

ANOVA or ANCOVA

I have to analyze a study where 2 treatments (t1 and t2) were used to control blood sugar levels. The 't2' is a new treatment which is being compared with an old established treatment 't1'. I have a ...
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1answer
22 views

Interpretation of significant interaction

I look for an intuitive understanding of interaction effect in ANOVA or regression. Let's keep things simple as the following. Suppose we have a standard 2 x 2 factorial design, where each factor ...
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1answer
38 views

Why do some parameters not appear in the matrix equation for an ANOVA model?

Here is the question I have been working on and this is the answer of it I realised $\beta_3$ is not in the $\beta$ matrix. I don't understand why. Can anyone please explain this?
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1answer
40 views

Is it valid to use quantile regression with only categorical predictors?

I am new to quantile regression and most of the examples I see are in a multiple regression context with continuous predictors. I am analyzing a designed experiment and was wondering if quantile ...
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14 views

How to statistically test if two continuous variables can combined to be proxies of one categorical variable? MANOVA?

In the dataset I have, there's one categorical variable (A) containing multiple levels. Due to multiple reasons, I want to use continuous variables only for modeling. I feel two other continuous ...
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35 views

Linear Model or Time Series Model or ANOVA?

I have some data: column 1 = dates (daily data from say 1st Jan 2014 to 1 July 2014) column 2 = person (about 10 different people) column 3 = sales made (daily data from say 1st Jan 2014 to 1 ...
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20 views

Hypothesis testing on groups of time series data

I have some experimental data from two groups, where each group contains data from $n$ subjects. The data are in the form of a time series for each subject, but are not all the same length. To be ...
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12 views

Apache Math package? OnewayANOVA

I am wondering have anybody used the Apache Math package to calculate the ANOVA scores? I didn't use SPSS as this can be incorporated into my JAVA code and is really light-weighted. Here is a link of ...
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ANOVA and Principal Component Regression

I Just need your valuable suggestions. ...
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Nested Anova for same group of participants

I am dealing with the following problem. I want to compare how some geometric measurements from the same participants can be connected with the existence of a disease. So the nested anova should like ...
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1answer
12 views

How valid is it to run one-way ANOVA on other means?

For background, I have a set of data where I asked two sets of 50 people to repeat a task 12 times, which generates a single number. Each 1x12 vector represents a single vector of data. I then group ...
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20 views

ANOVA test and its advantages

What are the advantages of using ANOVA test for large sample size and small sample size? I have read the advantages of anova but i can't differentiate them into the ones that are related to large ...
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1answer
58 views

Should the within-subject variability decrease?

I have a crossover experiment design, detailed as follows. there are 7 sites conducting the same experiment; In the experiment of each sites, 5 different treatments are administered to $n_i, \, (i = ...
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7 views

Full Model Vs ANCOVA

I have a general question- Say I have 2 categorical variables (Gender=1 or 0, and Color=1,or 0) and one continuous predictor:Scores. To fit the full model, do I include interaction between the ...
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1answer
20 views

Help need identifying analyses methods

Any and all help would be much appreciated! I've detailed a bit of information below, but if I left anything out please let me know My hypotheses are (info: NA= novel asssembly; S= selections or ...
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21 views

Variance assumption and normal assumption not met, Kruskal or Welch-Anova?

I have 7 different groups of playing time data that is not normal. Lets say its really not normal..like a lot. The variance is also not equal and fails the bartlett test by a landslide. Sample ...
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number of participants/analysis

Hi I am really struggling here any help would be muchly appreciated, please use laymen terms where possible. research question: a comparison of quit rates between 3 smoking cessation treatments. ...
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Unequal groups for One-way ANOVA

I have data for three unequal groups (grp 1 - N = 44), (grp 2 - N = 354) and (grp 3 - N = 347). Is it possible to compare all three groups running a one way ANOVA or is the first group too small? I ...
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40 views

Reporting an ANOVA with a continuous predictor (multiple regression)

I have a design involving 1 between-subjects categorical factor, 1 between-subjects continuous factor and 2 within-subjects categorical factors. This is theoretically a case of multiple regression, ...
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1answer
32 views

Choosing the correct statistical test

I have two datasets that describe reports of caregivers and parents from 8 daycares. The two data sets are matched by daycare's name. We want to merge the data into a single dataset that will contain ...
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58 views

ANOVA-type test but with known population variance of each group

I have a set of $N$ samples $s_{i}$, each one sampled from a normal distribution with standard deviations $\sigma_i$, which are known. I would like to know if the distributions have the same mean. I ...
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8 views

Follow up 2-way ANOVAs

I have a three-way significant interaction in a mixed-ANOVA, with two repeated-measures factors and one between-subjects factor. I would now like to follow it up with a repeated-measure ANOVA for each ...
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1answer
32 views

What is a one-way ANOVA on the ranks of the observations

While reading this link: http://www.statsdirect.com/help/Default.htm#nonparametric_methods/kruskal_wallis.htm, I came across the following: ...
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statistically analyse pass rate of test in different locations

I'm looking to analyse some data and as it's been a long time since my statistics days I'd like to know which area of statistics my problem lies. Lets say I have a number of different driving ...
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26 views

Simplifying explanatory model using Vegan adonis in R

I am a newbie to multivariate statistics, so please forgive me if this question is naïve, or if I have missed something important. I'd like to know whether it would be valid to approach using adonis ...
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8 views

Oral glucose tolerance test, comparing treatment groups over time SPSS

I have performed Oral glucose tolerance testing on 4 treatment groups (Control, Light exercise, medium exercise and high exercise) in which I took glucose readings at baseline, 30min, 60min, 90min and ...
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36 views

ANOVA comparing transformed data (with a constant) and untransformed normally distributed data

I am using an ANOVA to compare a number of outcome measures. Some of these are skewed and I've used a log10 transformation for them. As some of the values are zeros I've also added a constant of 1 in ...
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41 views

Estimating and comparing pre-post treatment effects in multiple pairs of treatment-vs-control groups

I have a dataset from an experiment where the goal was to study in which plant ecotype a treatment with a certain bacteria had the greatest effect. Hence the data consists of a number of control and ...
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15 views

F-Test in ANOVA with two within-Factors: why are there different denominators in the F-test?

in a two factorial ANOVA, the MS of Factor A (or B) as well as the interaction is divided by the MS of the residuals: e.g. F = MS_FactorA/MS_Residuals If I have two within factors, only the ...
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1answer
39 views

Repeated measures ANOVA and uneven number of trials

Suppose I have multiple responses from each subject in three different conditions (A, B, C). If I would decide to run a repeated measures ANOVA, I would first average over the repetitions from each ...
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1answer
53 views

What are the consequences of using ANOVA instead of Kruskal-Wallis on non-normally distributed data?

I am doing a high-school statistics assignment and am having trouble finding answer to this question. Anova and Kruskal-Wallis test are very confusing and I am lost trying to find and explanation to ...
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11 views

Best statistical method to answer relationship - User Participation Groups

I am working with large data set. In the data set we have user participation (some metric), their expert level and group they are belong to. ...
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40 views

How to cope with non-normal ANOVA residuals?

My data follow this outline: ...