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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Bartlett's test vs Levene's test

I am currently trying to address violations to ANOVA assumptions. I have used Shapiro-Wilk to test normality, and have dabbled with both Levene's test and Bartlett's test of variance equality. I have ...
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15 views

Is Randomized Complete Block Design a two-way anova?

Isn't Randomized Complete Block Design a two-way anova ? Can it be one-way ? As far i understand, since there is treatment effect and also block effect in RCBD, it is two-way anova. If i go to ...
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19 views

Randomized Block ANOVA Model: Intermediate Steps

While reading through my lecture notes, I came across a randomized block ANOVA model and some assumptions. How did the authors get to these assumptions (Expectation and Variance) from the given model? ...
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8 views

Using LIWC for ANOVA and pairwise analyses

I want to use a tool called Linguistic Inquiry and Word Count (LIWC) to analyze text data. As far as I know, it counts the number of words found in a given text that match a set of dimensions (e.g., ...
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18 views

finding relationships between variables in dataset [on hold]

I have a large project data set, which includes numeric values like dollar amounts, and non numeric quantities like country codes, purpose codes etc. I want to find relationships between the ...
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16 views

Nonparametric alternatives to 1-way anova?

Are there non-parametric alternatives to one-way analysis of variance? Ideally, I am looking for something that is easy to understand and can be done in SPSS.
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42 views

Can assumptions of a statistical test be tested post-hoc?

Suppose I ran 100 1-factor ANOVAs. I find some significant results. Now, since ANOVA has some assumptions, I should test if they hold. So, can I run for example Levene's tests (to check equity of ...
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9 views

Repeated measures ANOVA with custom standard errors

I want to see if there's a difference in size of some cells after several measurements, compared to a baseline (0.5, 1, 3, 6 hours versus 0 hours). I have 3 samples. Each measurement is actually a ...
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43 views

How to do a mixed (between- and within-subjects factors) ANOVA with Greenhouse-Geisser correction with {car}Anova in R?

I often have to do repeated-measures ANOVA with Greenhouse-Geisser or Huynh-Feldt corrections, so I use Anova (as described in ...
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9 views

extracting t value out of pairwise.t.test [migrated]

I would like to know if I could extract t values out of the pairwise.t.test function since it is only reporting the p values. I used the pairwise.t.test() for multiple comparisons after running a ...
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27 views

How to compare three groups to one control group without assuming equal variances?

I need to determine if one dependent variable (tensile strength) for each of three new groups is equivalent to that from my original ("control") group. I am not concerned with how the three new groups ...
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1answer
29 views

How to use ANOVA with two or more data points per condition per participant?

I'm preparing my first ever experiment for my PhD and am currently facing some difficulties with statistics. Here is my draft experimental design: 3 factors with 5, 3, 3 levels. As a result I have ...
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12 views

Means data in a regression Or Raw data in an anova? What's more appropriate?

I would like to learn what is the correct way to approach analysis of this data: I have 5 grasslands, and in each grassland I have 30 spiders. For each spider I have an estimate of what proportion of ...
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24 views

Tukey's test on two way ANOVA

So I have done a two way ANOVA, and would like to do a post-hoc Tukey's HSD test. What should I use for the $k$, SE, degrees of freedom and what is my $q$ and HSD? The exp is done in 4 places with ...
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35 views

Compare more than two means

New in statistics and I need your help regarding an easy question I think. I'm running out of time for my assignment so I kindly ask you to help me if possible. I'm running a pretest and the main ...
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18 views

Using stat methods on summary statistics

Is it ok to use statistical methods on summary statistics, as they're random variables? I ran into an interesting problem while working with a client, but will try to keep it very general as the ...
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24 views

Split Plot ANOVA in R

I have an experimental design in which I am comparing two or three types of soil (depending on how I group them) across two elevation transects. My overall goal is to compare different soil types, but ...
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13 views

Mean separation when interaction is significant

I am analyzing a factorial experiment in RCBD (3 cultivars x 4 inoculation methods with 10 replicates). All main effects and interactions are significant for a particular response variable. But in ...
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12 views

Mixed within-between ANOVA or MANOVA? [duplicate]

I am doing a research, the instrument of which is an English proficiency test that consists of two parts: one part is related to the test-takers' field of study and one part is unrelated. my ...
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11 views

Non-Parametric ANOVA: Repeated Measures with Replication

I'm struggling to find out which ANOVA test to use when you have a non-normal data set with repeated measures AND replication. I'm doing my data analysis in R and the friedman.test() method says it ...
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14 views

Multiple ANOVAs, then multiple Tukey HSDs, correcting for multiple comparisons

My experiment has 5 conditions (let's say Treatment A, B, C, D and E). There are 12 measurements (let's say Measurement 1-12). I'm running 12 ANOVAs on the measurements, I assume this means I should ...
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2answers
29 views

When to create a control group with paired T test

So if I wanted to measure the effect of a drug on a group of people, I think I would use a paired T test based on my research. But what if something caused a change in my group that I did not account ...
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12 views

Completely Randomized Experiment Design - Sum of Squared Error

I'm looking at a completely randomized design with one treatment factor. There are $\nu$ treatments and the $i^{th}$ treatment is observed $r_i$ times. There are no blocks. The model for this design ...
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22 views

Using G*Power to determine the sample size for an repeated measures ANOVA

I am currently designing an experiment that I want to analyze using an RM ANOVA. Since some of the factors are confounded I need to do multiple ANOVAS. One analysis will be for 2x2 factors (within ...
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21 views

Post-hoc analysis

Ok so maybe stupid question but I need to know, if im doing a post-hoc, and my experiment has two sources of variation, and one of them is significant and one is not. Do I only look at the means of ...
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39 views

Post-tests to consider in mixed models

I have a mixed model of the form y~condition + Replicate + Error(Replicate) but at the moment, and am running into difficulties in performing a post-hoc test. I ...
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26 views

Statistical comparison of multiple prediction models

I have a rather limited data set where for 100 subjects 30 attributes were measured before surgery and one attribute ($y$) was measured after surgery. About 20% of values are missing. The goal is to ...
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15 views

ANOVA, mixed model, or something else, for ordinal groups with a continuous outcome?

Possibly a simple / daft question so apologies in advance... Suppose I have several independent observations of a continuous variable, like height. The observations are grouped, and I would like to ...
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22 views

How does turning categorical variables into dummy variables affect ANOVA results?

I'm running a multiple linear regression with (amongst others) several categorical explanatory variables. My categorical variables are factors with several factor levels. For example, variable $x_1$ ...
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22 views

ANOVA analysis?

I need some help since I'm not that good with statistics. I have to perform a study to know whether different groups of people are willing to buy a product. I've shown 6 different scenarios, thus I ...
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22 views

Does robust regression affect contributions to explained variance by the different variables?

I've learned that in multiple linear regresion, parameter estimates as well as R$^2$ are not affected by using robust standard errors, i.e. are the same as resulting from non-robust regression. I now ...
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139 views

What is the null hypothesis of a MANOVA?

Background In order to analyze differences in some continuous variable between different groups (given by a categorical variable), one can perform a one-way ANOVA. If there are several explanatory ...
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1answer
29 views

How to caculate power analysis in a descriptive study

Hi I'm currently doing a dissertation, its a descriptive quantitative study. The method of data collection is a questionnaire scaled by a 10 point Likert scale. To calculate the sample population ...
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PERMANOVA Design

My aim is to quantify temporal change in community composition by measuring community composition through time at several plots using randomly placed quadrats. The idea would be to repeat surveys at ...
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Why does adding more terms into a linear model always increase the r-squared value?

Many statistics textbooks state that adding more terms into a linear model always reduces the sum of squares and in turn increases the r-squared value. This has led to the use of the adjusted ...
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36 views

paired t-tests and interpretation of results

My study is about comparing the scores a group of students (sample, N=14) in two different conditions. They play the same game in a tablet and using a computer. They were administered with a ...
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45 views

How to test whether people remembered more items given an intervention administered within subjects?

I have 20 individuals who memorised 5 lists of information. They immediately recalled the information, then at the end of the day either received an interventional 'cue' or nothing prior to recalling ...
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1answer
45 views

Diagonal lines in residuals vs fitted values plot for ANOVA

I'm experiencing strange patterns of residuals. The following chart is a scatterplot of Standard residuals (Sres) versus Fits. I'm interested in the diagonal lines that mean that a higher fit leads to ...
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37 views

BINARY or ANOVA test in R

I'm confused on what test to use for an experiment I have conducted over the past months. Let me give you some context: I ran a germination experiment, sowed 900 seeds total in trays of 40 in a ...
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1answer
31 views

When or why do i utilize the repeated measure design in my analysis?

I know the Repeated measures ANOVA is the equivalent of the one-way ANOVA, but for related, not independent groups but I can't understand. When can I use this design? When one way? And when repeated ...
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10 views

Variable independency

I have done a feeding trial with 4 Cages With Fish, 200 Fish in each Cage. Two cages recieved feeding regime I and two cages recieved feeding regime II. In addition each feeding regime had one cage ...
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Non-parametric Levene's test by Nordstokke and Zumbo

The example they mention is using a one-way ANOVA. What if I have two factors (3x11) and a dependent variable, can I do a two-way ANOVA to calculate the univariate levene's test? If so, how would I ...
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How to get ANOVA table with robust standard errors?

I am running a pooled OLS regression using the plm package in R. Though, my question is more about basic statistics, so I try posting it here first ;) Since my regression results yield ...
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1answer
27 views

Do unequal sample sizes matter for 1-factor analysis of variance if the sample variances are similar?

Suppose I have five samples with unequal sample sizes (50, 9, 10, 30, 15). If the variances of the samples are similar (e.g. p>0.05 from Levene's test), is it OK to use 1-factor analysis of variance ...
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123 views

Timing attacks: When the time to complete two different tasks are statistically indistinguishable

This question is related to the open source security package for node/Javascript called credentials, and in particular how to evaluate whether a comparison of two strings is "constant time", though ...
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Multiple testing with one-factor analysis of variance

I have groups A (N=60), B (N=30), and C (N=30), and 100 variables. Using one-factor analysis of variance (F-test), I would like test whether the three samples differ for each variable. So, if I first ...
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1answer
98 views

How to follow up a factorial MANOVA with discriminant analysis?

This is a follow-up to to my previous question: How can MANOVA report a significant difference when none of the univariate ANOVAs reaches significance? I have two IVs with each having three levels ...
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102 views

Departure from normality assumption in ANOVA: is kurtosis or skewness more important?

Applied linear statistical models by Kutner et al. states the following concerning departures from the normality assumption of ANOVA models: Kurtosis of the error distribution (either more or less ...
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Proportion of variance in dependent variable accounted for by predictors in a mixed effects model

Let say I've ran this linear regression: lm_mtcars <- lm(mpg ~ wt + vs, mtcars) I can use anova() to see the amount of ...
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continuous variables changed into categorical variable for ANOVA

I have two DVs and i measured them on continuous scale. one DV is normally distributed other is not. And i have three IVs and i measured them on continuous scale. But later on i planned to conduct ...