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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What type of analysis

I have two data sets to compare. Each is a list of billed amounts by diagnosis codes. The data differs in that the diagnosis codes may be different for some of the billed amounts. There are ...
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Aligned Rank Transform for mixed effects ANOVA in SPSS

In a book, I've found SPSS syntax for performing an aligned rank transformation in a two way ANOVA. The procedure is: - save residuals by performing a standard ANOVA - use Aggregate to determine ...
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27 views

How to calculate p value from ANOVA function for LMM results?

I have used ANOVA function so that I can get the overall p value of significant factors: ...
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ANOVA in R: How MSresiduals are estimated when using Error(interaction)?

I have checked from the existing answers, but I got not answer to my question. Although I learnt on other issues, this webpage is a very nice tool. I will be using it from now on. And this is why I ...
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23 views

SPSS Contrasts for a Five-Way Within-Subjects ANOVA (Yes, You read correctly)

I have a 4 x 4 x 2 x 2 x 2 repeated measures design and I'm trying to test a contrast for just the first variable (here called "SOA"), averaging over the others, in SPSS. Initially, I thought it ...
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30 views

Reproducing simple t-test result with ANOVA

We know that a t-test is just a special case of ANOVA, so I tried to reproduce the result of the following t-test with aov() or ...
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1answer
36 views

Regressing, analysing data with points rather than polynomial?

I am looking into making a regression of a bunch of data that is contained on some range of real numbers. In my case, x is between 0 and 1 and y is between 0 and 10. If I have 150 data points on this ...
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1answer
24 views

Orthogonal contrasts for four levels - are Helmert contrasts orthogonal?

I am planning to do a 2-way mixed ANOVA with the within-subjects factor having four levels. Since the exact data do not matter, I hope to suffice by only providing a general question. On my ...
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40 views

Which post-hoc comparison to use and why

Hopefully this is now a much clearer picture of the question I want to answer: For each of 60 different plans I ran 35 simulation replications of my Agent Based Model (ABM) simulation. Then for each ...
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20 views

propagating errors through an ANOVA?

I'm sorry if this question has been answered before. I have a dataset: -1.5 -1.8 -1.625 -1.25 -1.525 -1.675 -1.15 -1.35 -1.65 etc Each column is ...
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Homogeneity of variance for time variable

I have four groups of plant treated with different temperatures and I conducted repeated measurement on their growth rate. I use ANOVA with Mixed Model to analyze the data by specifying both ...
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Appropriate analysis for this experimental design - non-normal data

I've run an experiment with 8 subjects, which had to perform [a series of 4] navigational tasks under 4 different vision conditions each. The experiment was repeated weekly, 16 times with the same ...
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2answers
24 views

Directional research hypotheses vs. directional hypothesis testing

When I took a methods course, I was told to avoid making a directional hypothesis. I understand the reason. Now however, I often see hypotheses like these: "We hypothesized that reaction time will ...
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1answer
38 views

ANOVA and Count/Percent Data

I'm just starting to work with some count data and I'm still trying to understand some of the complexities of it, so any help would be greatly appreciated. First the simple version, and then the ...
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15 views

Factorial design for interactions with ordinal DV

I want to make a 4 question, multiple choice survey in which each question asks about an analogous range of actions for slightly different scenarios. Each participant would only be administered the ...
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1answer
12 views

Which test do I use; need to compare tests with one another pre and post intervention

I am writing a thesis on the validity of balance training tests. I need to compare the tests and see if they correlate with one another in testing balance in the elderly. There's a control and ...
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18 views

ANOVA and dependence WITHIN a group

I have three different methods that I would like to compare using ANOVA. The variable to compare is method accuracy that I get trough cross-validation. This means that the same data set (N=60 ...
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2answers
48 views

Homogeneity of variance in linear mixed model

I am confused by the assumption of homogeneity of variance of the Linear mixed model. Does homogeneity of variance equal to homogeneity of error? May I know is the homogeneity of variance referring ...
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1answer
35 views

How to correct the degrees of freedom?

I'm running mixed design ANOVA using R. Somehow, I got incorrect values for the degrees of freedom (Df). There are two factors: temperature (2 levels) and ...
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28 views

Correct use of Mixed model for random block design?

I have the following experimental design (random block design). Block with 4 Treatments (A, B, C, D) repeated at 4 different sites. Treatments were applied to individuals of different species (factor ...
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21 views

ANOVA's and reaction time data

I've been reading a lot on the effect of perceptual load on selective attention but the analysis confuses me somewhat. Some of these studies flag 20-40ms differences between conditions as significant ...
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68 views

How to model the effect of time in a balanced repeated measures design with 2 measures each at baseline, during instruction and post instruction?

I want to examine growth for 38 participants. I have 2 scores at each of 3 separate phases of instruction - baseline, during instruction, and post instruction. Restated, I have 2 baseline scores, 2 ...
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13 views

How to structure data for SPSS (percentages for log-linear analysis)?

I am a bit desperate because I am writing my Msc thesis and I am not sure how to organize my data for an SPSS usage. My research examines the performance of mobile banner campaigns and how the 3 ...
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1answer
63 views

Testing the variance part of a Generalized Linear Model out of sample

Suppose I have a response vector and an ANOVA design (for simplicity, assume it’s a one-way ANOVA with two treatments). A few Generalized Linear Models (Poisson, Negative Binomial, etc) are fitted to ...
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15 views

ANOVA to test overall significance of model in linear regression with only continuous predictors

A normal ANOVA model always needs a categorical variable as a predictor(the factor/group) right? Please let me know the reason if you think otherwise. So in case of a linear regression with only ...
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21 views

Non parametric anova or two non parametric ttest?

I have a statistical question about a project I recently got. We performed a flow cytometry assay on 3 different groups: controls (n=5), patients before treatment (n=5) and paired patients after ...
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43 views

Two-way repeated measures ANOVA with unbalanced data

I have a system / operator repeated measures data set for which I would like to answer the questions: is system 1 quicker than system 2 is operator 1 quicker than operator 2 does the order of using ...
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Determining dependancy of observations

I have 12 people, 6 in treatment group and 6 in control group. They gave ratings (1 to 7) to 8 different activities they were performing as a part of the experiment. I looked at another thread here ...
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55 views

How do I perform this complicated ANOVA type analysis in R?

I have the following type of dataset: | | | variable_r | subject | gender | age_group | Cond_1 | Cond_2 | ...
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1answer
55 views

$\textit{Post hoc}$ test after repeated measures ANOVA (LME + Multcomp)

I have a dataset where the samples are dependent, belong to different groups, and measurements were taken over time. It looks like this: Subject Group Time Value S1 G1 12h 5.55 S1 G1 24h ...
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How to analyze this design? Multiple batches of Single group pre-test post-test designs

first of all - thanks for reading this. I have a want to analyze the effect of an intervention, but due to practical circumstances I cannot randomly assign people to it and the interventions differ ...
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32 views

How to confirm a two-way interaction in a three-way ANOVA model using SPSS

I have two groups of subjects, both undergoing two experimental conditions, and data are collected at two time points: pre- and post- condition. I run a 3-way ANOVA, with one between subject factor ...
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16 views

Can I use mixed ANOVA with 2 groups and 2 time points

I have 2 groups (biomaker high vs. low) and I measured quality of life (QoL) score (continuous variable) on 2 time-points. I want to run interaction statistics (group*time) to assess the effect of ...
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1answer
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ANOVA with repeated mesures - No random groups

I have 4 groups, 3 of them receiving a treatment and the last nothing. I will do two mesures, before and after the treatment. But my groups are pre-defined, not resulting of a random selection. Is ...
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39 views

Regression says $H_1$ is accepted, One-Way ANOVA says $H_1$ is rejected. Are different results possible?

I am testing my hypotheses with a 2x2x2 between subjects design. Thus I am testing the moderation effects on the dependent variable. When I used regression to conduct this test, $H_1$ was accepted. ...
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Why am I getting a 10-15% type I error rate for a 2 x 2 ANOVA?

While testing type I error rate using R, I found that I am getting higher than 5% false positives with a 2-way ANOVA. However, I thought one of the reasons for using an ANOVA (as opposed to multiple ...
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How to adjust for multiple comparisons with a large number of ANOVAs?

I have a complex experimental design: 3 groups, each of which come on 4 occassions and I obtain recordings from 250 skin electrodes. I am interested in knowing which of the electrodes provides a ...
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16 views

Two way ANOVA or ANCOVA

I need to show that BMI of adults is neither age nor gender specific. Should I do ANCOVA or randomly make age groups and do two way ANOVA?
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How can I perform a post hoc test of a three-way interaction in SPSS using the 'test' command?

I will describe the design of the experiment briefly. The task have two within-subject variables ($A$ and $B$), A. have two levels B. have three levels one repeated variable with 5 levels ('time ...
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1answer
32 views

Can I use ANOVA if a sample is not normally distributed

My data are not normally distributed. I have to compare three groups for their achievement in skill learning. $n=4$ in each group. I have used three methods ($M1$, $M2$ and $M3$) to teach one skill to ...
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10 views

Logtransforming pre and post data

I have pre and post data from a working memory test (following an intervention) that I am going to use in a mixed ANOVA. I have log transformed my post data because it was skewed, adding on 10 because ...
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1answer
38 views

Beginning anova in R: Phantom significance when testing for interaction terms

Suppose I create a dummy scenario as such: > A <- rnorm(10000) > B <- rnorm(10000) > C <- rnorm(10000) > Y <- A*B + rnorm(10000,sd=0.1) ...
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38 views

How to test differences of means of 3 independent groups

I'm new to statistics and the only software i know how to use is SPSS. I need help.... I have 3 independent groups with sizes: 24, 27, 37. I wanted to test the difference between the means of their ...
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1answer
39 views

Constrained Maximization and Likelihood Ratio Tests for Nested Linear Models

Suppose $\boldsymbol \beta \in \mathbb{R}^k$ is a vector of coefficients for a generalized linear model with $g \left[ E(Y|X) \right] = X\beta$ for a link function $g$ and I wish to test the composite ...
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1answer
32 views

Can repeated measures ANOVA be used with only 2 time points?

I am analyzing my data of my experiment and I have a question concerning the repeated measures ANOVA. I have 2 independent variables (temperature and salinity), 1 dependent which is length and 2 ...
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23 views

Mean accuracy for sum of squares/variance

Formality says that when computing the sample variance or sum of squares one computes a sample mean with the sample data given. If for some reason I had access to a better estimate of the mean (from ...
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34 views

Repeated measure two-way ANOVA (non-parametric)

Non-parametric ANOVA – a hot topic that is unanswered. There are many questions on this topic online. However, they all seem to end in a debate and no definite answer or clear explanation (that I ...
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1answer
20 views

Assumptions of two way anova

Please tell me what the actual assumptions of a two way anova are. I read somewhere that this being similar to multiple regression, the only assumption is that the residuals are to be normally ...
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37 views

ANOVA to find subjects that responded significantly different between treatments

I have a dataset composed of several subjects exposed to two different treatments (treat) in three distinct times (test), and I am interested in highlighting which subjects have significantly ...
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1answer
30 views

Post-anova item analysis

Does the following corresponds to an existing process? N subjects are subjected to m test items. 2 between-subject factors are manipulated with 2 modalities each. An ANOVA reveals that one of the ...