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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How to estimate variance components with lmer for models with random effects and compare them with lme results
I performed an experiment where I raised different families coming from two different source populations, where each family was split up into a different treatments. After the experiment I measured ...
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123 views
Phylogenetic dependent variables: ANOVA?
I understand deriving a covariance matrix from phylogenetic data to make $cov(X,Y) = 0$ for two variables you're making a regression on. But what happens if you have one continuous variable, that ...
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690 views
How to analyse repeated measure ANOVA with three or more conditions presented in randomised order?
Context:
My question concerns a typical design in my area – a researcher takes a group of subjects (say 10) and then applies three different conditions to them to measure the change in a response ...
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132 views
Type III sums of squares
I have a linear regression model with one categorical variable $A$ (male & female) and one continuous variable $B$.
I set up contrasts codes in R with ...
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96 views
Estimating comparative success of different brochures
The Real World Problem
One of my clients is preparing to send a direct mailer to their subscribed user list, and this statistical challenge came up.
Their marketing team has 3 different brochures, ...
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373 views
How to compute confidence interval in ANOVA with repeated measures?
I made a model using repeated measures univariate ANOVA in R.
...
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63 views
Comparing models of different types of ANOVA - multiple comparisons?
Statistical semi-novice question:
Just following up this question, the fact that the three types of ANOVA exist with an unbalanced design, and that (presumably) you don't necessarily know a priori ...
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78 views
When can I leave counterbalancing factors (between participants) in an ANOVA out of a write up?
The following is a problem that I keep encountering in different forms. For now, I give one example, but I would also be interested in the answers to the more general question.
I have a design with a ...
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32 views
Experimental design for complex temporal pair interaction data
Context: I am faced with what I believe is a non-trivial modelling problem that I have been assigned as part of my post-doc. My expertise is in the area of graph / network theory so I have found ...
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82 views
When to use a chi-squared test?
This is a very basic question however I do not have a statistical background and I am currently analysing some data for my dissertation.
I have constructed a survey about healthy lifestyles & ...
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108 views
Specification of error terms in aov() in R
For a two-way repeated measures design, we can specify the model using aov in the following fashion:
...
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87 views
ANOVA claims that model is singular
I have a problem with a 3 way ANOVA with repeated measures.
The design is the following: "localization" is the dependent variable, than I have the following within subjects factors "material" (4 ...
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78 views
Can paired samples be treated as un-paired for 1-way ANOVA
This may be too simple a question for this forum - it is possibly a very basic statistics question as commonly found in biomedical research. But since scientists often lack good understanding of ...
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52 views
Comparing results to 50% chance with ANOVA
I've been having a difficult time looking for a solution to this one, though it seems easy enough. I'm trying to replicate an experiment (Fukumura, van Gompel 2010, JoMaL) which was constructed as ...
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87 views
Violation of independence, ANOVA
I have been asked to analyze data from field observations of a fish community.
Data are collected in two sampling-sites during 16 days (nonconsecutive), twice a day. Dependent variable is biomass.
...
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180 views
Unfold degrees of freedom of interaction in factorial design analysis in R
I've been trying to analyse data from a factorial design with missing cells without much success until now. I'm using Anova from car package, that, according with I've read, can handle unbalanced data ...
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79 views
Using $\chi^2$ to compare two Markov transition matrices
I have a set of observed Markov sequences for which I have calculated first and second order transition matrices:
$$M={P}(X_i=x_i|X_{i-1}=x_j)$$ and $$M^2=P(X_i=x_i|X_{i-1}=x_j,\,X_{i-2}=x_i )$$.
I ...
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Non-significant group effect, but LSD post hoc is significant. Why?
I am performing repeated ANOVAs in SPSS and came across something I don't understand.
Basically, the main effect of group (I have three groups) is not significant (p = .062), but the LSD post hoc ...
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126 views
How to test for differences in binary score data?
I have data from a human subject study that was setup as a 3x2 (system by task type) experiment, with 24 participants. Each participant completed 6 tasks in all, one using each of the 3 systems, and 2 ...
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160 views
How can I compute a repeated measurement ANOVA with a mixed model?
It is my task to program a mixed model. The data is from 20 experimental subjects, who were measured under 2 factors. Factor A has 7 levels, factor B has 3 levels. So, that for every subject I got 21 ...
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182 views
Missing cells with Type III SS
I have a linear model of the form y ~ x + z + x:z.
I have unbalanced data and further have a few missing cells (data would be unbalanced even without those missing cells).
My understanding of the ...
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290 views
How to choose between nested or split-plot analysis of variance?
I am having serious problems understanding the type of design I have, I would appreciate any help you can give me to understand it:
I have 324 data points, and four factors:
...
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237 views
Formulating a mixed model with nested fixed and random effects
I'm analysing the results of an experiment using a mixed (fixed and random-effects) ANOVA with nested effects and I just need someone to confirm that I have the right model.
The effects in the design ...
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162 views
Weighted regression for categorical variables
I have been trying to use weighted regression on some data where there are three categorical variables with the
lm(y ~ A*B*C)
command in R.
This was to try ...
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230 views
The order of variables in anova matter, don't they?
Am I correct to understand that the order in which variables are specified in a multifactorial ANOVA makes a difference but that the order does not matter when doing a multiple linear regression?
So ...
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Repeated measures ANOVA in R for non-orthogonal design
I have data from a two-factor within-subjects experiment design where the conditions are not orthogonal. Factor one (Location) has three levels; factor two (Stimulus) has three levels, one of which is ...
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Pretest-posttest plus control design
I am evaluating the effect of an intervention (treatment: a lecture) on the ability to spot behavioral clues of emotions using visual stimuli using pretest-posttest plus control group experimental ...
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Two uneven groups (101 vs 21) measured twice; what repeated measures ANOVA equivalent can help?
I have a question that I have difficulties in answering:
I have two groups of patients tested twice at the same continuous variable.
Group A=104 & GroupB=21.
So two groups, one continuous ...
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77 views
Can I trust the result of a one-way ANOVA with many treatments each with very few replicates
I am doing a one-way ANOVA of a response variable (Y) on a treatment factor (T) of 7 levels. However, for each treatment, I have only 2 observations (or replicates). The ANOVA result shows the the ...
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55 views
ANOVA variable that is both BETWEEN & WITHIN
Does anyone know how / if can you treat an independent variable as BOTH a between AND within subjects variable (ideally in SPSS ANOVA-repeated measures). That is, we have a repeated measures study ...
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95 views
Effects of multiple within-subjects factors when not all combinations of levels are available
My question: how can I analyze the effects of multiple within-subjects factors when my design does NOT include the all combinations of their factor levels, as would be required by a standard factorial ...
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212 views
Split-split-split plot cross-over design… is this even possible?
I'm doing statistical analysis on a psychology study I ran a short while ago, and I'm starting to think that I've designed myself into a corner.
In the study, we measured participants' pointing ...
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577 views
Non-normal and heterogeneous data with repeated measures ANOVA
I have run a repeated measures ANOVA using 3 groups and one factor with two levels.
I have discovered that the data are not normally distributed (but not badly), nor is the variance homogeneous in ...
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219 views
One-way repeated measures ANOVA and missing data
I have following data for the one-way repeated measures ANOVA test and I don't know how to deal with missing values.
The data looks something like this:
...
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173 views
Effect of mediating variable independent of effect of possible covariate
Here is a rather involved question. It can be summed up as follows: how can I test the effect of a potential mediating variable, independent of the effect of a possible covariate with which it is ...
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504 views
Is it mathematically justifiable to log transform variables before running an ANOVA?
I have a model with variables (financial ratios) and some of them are in percentages, some in days and some just ratios (negative and positive). I ran an ANOVA and the results were not so good. When I ...
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133 views
Can I used a repeated measures ANOVA or do I have to use a multivariate ANOVA?
I don't feel very comfortable with stats (still using simple programmes like SPSS rather than R!), and have a question about which is the best test to use with the following design:
I have performed ...
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140 views
How to test and examine interaction effect in 2 by 3 by 6 mixed ANOVA design?
Background:
I have two groups of children - one group with normal hearing and one with permanent hearing losses - call them NH and PHL.
Each child has had a hearing test, consisting of 6 different ...
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305 views
2x2x2 plus control group: nested ANOVA?
I recently ran an experiment assessing the impact of three system factors (factor A; factor B; factor C) on user attitudes (4-item scale). Each system factor had two levels (high vs. low). As a ...
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374 views
Using variations of ANCOVA for non-normal distributions
My first question here, hope to be relevant to the community. Im into CS course and a total rookie on statistics, so let me know if more detail is needed and I will edit the post.
I have a problem ...
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Capturing the relationships among model variables based on ANOVA table
While studying ANOVA analysis, I meet an example related to the ANOVA table given in the attached figure
Here,
Y stands for change in hemoglobin (%)
X1 stands for duration of the ...
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111 views
How to do post-hoc contrasts on within factor depending on certain between groups in SPSS?
Here are my experimental factors:
within-factor (two levels): time1, time2.
between factor (four levels): 4 groups.
I want to test specific post-hoc contrasts comparing:
group1: time1 vs. time2
...
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131 views
Initial conditions of experimental units in Completely Randomized Design
Since I had no answer to the second part of this question I would like to ask it again providing some more infos I gathered in the meantime.
Context
We are designing a complete randomized trial in a ...
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392 views
How to analyze an unbalanced within-subject ANOVA design?
I have data from an experiment involving 4 groups of subjects, 2 possible interventions first and 3 possible intervention at a 2nd point, repeated data measurements from each subjects multiple time ...
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79 views
Analysis of multimodal metric response variables linked to a categorical variable
my level of stats is kind of restricted to some undergraduate courses.
Anyhow I received some data from a planned experiment. Basically it is about to test the shear strength (interval scale) for ...
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264 views
Is this a two way ANOVA with replicates?
I have the following results from a biological experiment. I measure the size of the sample (2,4,8,16,32 or 64) and count its distribution in a population of 50 (sum of counts=50). I do those ...
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156 views
Two-sample t-test / ANOVA on functions, with unequal variances
Suppose $N$ experiments can be made in varying conditions. Each of them yields an estimate $f_i$ of a continuous (and, if necessary, positive) function of x over some interval. Experiment $i$ is ...
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218 views
How to implement a weighted 3-way ANOVA in unbalanced design?
I have implemented a three-way anova with type III sum of squares in c++. Since some of my experiments (observations) are more important (more informative), I want to give them a higher weight in my ...
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347 views
What is a good statistical test for independent replicates?
I have a series of measurements in which something is sampled and placed into either category 1 or category 2. I have 3x2x3 factors for each set of measurements, and each set of measurements is done ...
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When to average samples?
My question is when to average samples or when it is allowed to apply a mixed effects model.
I have the following constellation:
there is a cell-line experiment conducted in a 96-wellplate, meaning ...
