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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50 views

Should I remove the outlier?

I want to run an ANOVA test. I am therefore testing for normality. I have tested each group and the residuals (group together)for normality. My data sample does not look approximately normal. However ...
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14 views

1-way vs. 2-way Anova (or non-parametric tests)

I am new to statistics and ecology and am doing this data analysis for bird count data. We have 3 treatments (which is 1 factor with 3 levels) and 2 sites (which are considered replicates as per ...
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16 views

How to do a within subjects ANOVA when comparing the same thing but with different units?

So I am trying to compare a group's performance on a test over the course of three measurements. The grading scale for the test is from 1 to 100 points in the first two measurements, and for the ...
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10 views

Moderation analysis for repeated measures ANOVA [on hold]

My dataset looks like this: My hypothesis is that the statistical differences between the within-subjects measures (A1 vs A2 vs A3) are moderated by a third variable (mod) which is continuous. What ...
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7 views

What is the difference between these mixed ANOVA specifications

I am trying to perform a mixed ANOVA analysis with one between subject and two within subject factors. Some Experiment information Two groups of 17 subjects (old and young participant group) Three ...
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11 views

Anova with order between treatments

I want to analyse a regression model with categorical explanatory variable. to be accurate, the model is as follows: $y_{k,j}=\mu_k+\epsilon_{k,j}$ where $k$ is the number of different effects $(k&...
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1answer
46 views

Difference between normality of residuals vs normality in each group.

I've been searching on the internet and books for quite a long time now and have come to the conclusion that normality of the residuals (each values minus the mean of each group) is the same as ...
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17 views

In SPSS, what follow-up tests for a three-way repeated measures ANOVA with no 3-way interaction?

For a three-way repeated measures ANOVA: Do I use simple main effects syntax or run t-tests in SPSS in my follow up analyses (pairwise comparisons?) for a non-significant three-way interaction, with 1 ...
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7 views

Main effect in 4 X 2 RM ANOVA found - are post-hoc tests for interactions allowed?

I ran a repeated measures ANOVA (two measurement levels, pre and post) with 4 between-subjects groups. There is a main effect of time, i.e., pre and post measurements across all 4 groups are ...
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1answer
32 views

Mixed factor both “within” and “between” subjects

I am wondering about experimental designs in which the levels of a factor are partly within and partly between subjects. Assume for concreteness that the experiment is as follows: The response ...
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11 views

Missing rows ANOVA in R [closed]

Why does the S:x1 column disappear (presumably S:x1 goes into ID but I dont know why)? S is a factor, x1 is a covariate and ID is a factor. ...
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14 views

Kruskal-wallis v ANOVA v robust methods

I have data from 3 groups which don't follow a normal distribution, my sample sizes are ~600 for the control group and ~300 for the test ones. I made a density plot of the data which looks like: ...
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5 views

Impute, leave N/As as-is, or create a threshold value?

I have a dataset in which people complete background checks and have found that, for those who complete them, time to completion is a very significant indicator of whether they will or will not ...
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5 views

How to weight a repeated measures factor in a three-factorial design?

I have a design with three factors. two of them are categorical between-subject factors: relationship closeness (close/distant) and experienced trauma (yes/no) The third factor is a repeated ...
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0answers
12 views

multiple t-test vs ANOVA

I've an naive question, I haven't a statistician background so sorry if I can't express myself. Imagine this situation, I have several sample groups (control, treatment 1, treatment 2, ...). I would ...
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0answers
21 views

Difference in mean change between groups - which statistical test to use?

I have three groups for which I have baseline and final measurement values (and intermediate, but that doesn't really pertain to this question). I want to use a statistical test on the mean change ...
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1answer
50 views

Why does ANOVA give different results when a binary factor is treated as numeric?

I've encountered several times the situation where ANOVA gives drastically different results depending on whether the variable is entered as a factor or as a numeric variable. Why is this the case? I ...
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0answers
10 views

Meta-analysis for crossed design?

Is there a way to do meta-analysis for crossed designs (no control group)? I have a 2x2 factorial with count data that I would be interested in looking at. I basically did the same experiment five ...
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1answer
28 views

aov() command reading formula

Does anyone know how R computes the model matrix from a formula in aov() or lm()? I wonder about some things. Just assume the models below makes sense (although it might not). You have factor S with ...
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2answers
41 views

Calculate interaction sum of squares by hand

I'm trying to manually calculate the sums of squares (SSs) in a two-way ANOVA in Python. However, I cannot seem to get the correct result for the interaction SS. I'm using the ...
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0answers
18 views

Mixed ANOVA: 2 within subjects factors, 1 between subject factor

I did an experiment where I had two groups A (22 subj) and B (19 subj) receiving different treatments, performing a task with 3 conditions, cond1, cond2, cond3, in 2 moments (pre and post treatment). ...
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1answer
14 views

Can I just log transform a dependent variable (to remove heteroscedasticity) without transforming the independent variables in a 3 way ANOVA?

I'm trying to analyse a data set using an ANOVA but have significant heteroscedasticity - transforming the DV using a log-transformation seems to remove this issue, but I wanted to check if I should ...
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0answers
11 views

Is having more features definitely equal to having a higher chance of overfitting?

I am doing a EEG data classification problem. Currently I am using the ANOVA test to help me select K best input features (with K a parameter to tune) and feeding the selected features into a logistic ...
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4 views

How can I compare the impact of two pre-post interventions when they have unequal baselines?

I have some data I need to analyse in order to test the influence of two different kinds of menus on subsequent sandwich purchases. We had one menu in one venue, and the second in another. However, ...
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10 views

Statistical Analysis on Multiple Group Data

I am new in statistical analysis field. I have a dataset which is divided into five groups each with four columns(common in all five groups). All these five groups have a baseline group to be ...
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1answer
21 views

R: anova() vs. Anova() for test of categorical predictor from glmer or glm.nb object

In R, I'm wondering how the functions anova() (stats package) and Anova() (...
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8 views

How to do contrasts in a significant interaction of 2 variables in a 4 four variable set?

I did an analysis of a 2x2x2x2 mixed factorial anova. The first 3 variables were repeated measures and the last was a between groups analysis. The data in the repeated measures were all reaction ...
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Full-Factorial Design (3^2): Not sure about right method for analysis

I ran an experiment (online-survey) showing venture capitalists 9 fictional startups that only differed in factor 1 and factor 2. Both factors had three levels: Factor 1 = 50,250,450; Factor 2 = 0.5,1,...
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33 views

Fixed Effects in a model I ANOVA. Why should the parameters sum to zero?

Let our model be: $X_{ij}=\mu+\alpha_i+\epsilon_{ij}$, with $\epsilon_{ij}\sim^{iid}N(0,\sigma^2)$. The $\alpha_i$ is the fixed-effect, and $i \in \{1,...,m\}$, $j\in \{1,...,n_i\}$. If we have $m+1$ ...
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13 views

Interaction Contrasts in SPSS

I am trying to run a 2x2 MANOVA with two sets of categorical independent variables (V1: healthy weight vs. overweight) (V2: binge eating diagnosis vs. healthy controls), on continuous dependent ...
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6 views

ANOVA planned (a priori) tests

Can anybody tell me which ANOVA planned (a priori) tests exist? Which are their characteristics? How and when are they used? As I´m beginner in this area it would be also useful in someone could ...
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6 views

Do I need to use a repeated measures statistical test for my data?

I conducted an analysis over three different time periods, investigating if there is a difference across time periods to how strongly my subjects react to two different stimuli. What I'm interested in ...
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14 views

Should I use t-test or ANOVA+post hoc (two different treatments and a control)

I have been working with ice algaes,and Im looking on their fattyacids. Here is a bit about the experimental design. I have one treatment area, cleared, where I have removed all snow. I have ...
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1answer
27 views

Can I report simple main effects without an interaction effect?

I have a quick question about reporting simple main effects. I am running a two-way mixed ANOVA and the interaction effect was not significant. I understand that if you have no significant interaction ...
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8 views

Post hoc non-parametric tests

I am analyzing some data that has violated assumptions of ANOVA and am using the WRS2 package in R. I am concerned about the post hoc tests. I am comparing three groups, Dx, (schizophrenia, ...
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0answers
14 views

ANOVA with standard deviation as the dependant variable

I have some experimental data collected from 5 separate treatments. Each group comprises a set of independent time series measuring the property I am interested in. The sample sizing (i.e. number of ...
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0answers
13 views

Test signifance of each slope (corresponding to each level of a factor) in ANCOVA in R

Using Ancova, we can test the homogeneity of slope (or intercept) across different level of the a factor. Is there a way to test whether the individual slope is significantly different from zero using ...
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23 views

Determining the correct test for experiment design

I'm trying to figure out the right test to use for my experimental design, I was hoping someone here could help. Here's the structure: Two independent variables, IV1 and IV2. IV1 has 3 levels, IV2 ...
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14 views

Comparison: Exponential Regression vs Quadratic Polynomial Regression

See this file here: Decay.TXT. I first tried to fit the logarithmic model first ...
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9 views

Interpretation of p-value for F-change

I'm having troubles with interpreting the following results. If I'm not mistaken, Sig. in the ANOVA table means that the R Square is significant. That is good news. ...
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1answer
24 views

Comparing two models through ANOVA with different types of functions

See this file here: Decay.TXT. I first tried to fit the logarithmic model first ...
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4answers
346 views

Appropriate data transformation

I have two dependent variables y1 and y2 with highly skewed distributions. In order to do ANOVA, I was trying to transform the ...
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20 views

How to analyse this hierarchical-like data better?

I have a dataset whose structure is as below. Here f1, f2, f3 etc are a set of features. There are differennt models to predict each Vi from all fjs. There are different models to predict each Wi ...
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15 views

Non parametric (or parametric) two way ANOVA in case of heteroscedasticity [duplicate]

I've got the following data set: 2 independent variables (age, with 4 levels, formulation, with 2 levels) and 1 dependent variable (consistency of cheese slices). I've tested the ANOVA assumption of ...
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0answers
19 views

Testing for significant differences between mutiple groups (some not normally distributed)

I have been trying to process data I collected in R, but not getting anywhere, so I hope someone can help me out. My question could be interesting for anyone who wants to compare more than 2 groups ...
3
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1answer
86 views

How to ascribe and defend statistical significance in linear regression. P-value interpretation and alternatives

I am studying a treatment that degrades device quality and performed an independent sample test on two batches that had different initial quality. I analyzed the data with a two variable linear ...
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1answer
38 views

How can you test if a series of observations is significantly increasing?

For each subject, I have a series of numbers (d-prime) that increase depending on SOA. I'd like to show that these values are increasing up to some certain SOA. What would be the best test? I did a ...
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20 views

Using an LMM for whole set of data vs using ANOVA for subsets

I did an experiment where I presented animals with 2 different stimuli over 3 different time periods. I'm interested to see if they show a statistically significant difference in response to the two ...
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46 views

Pairwise post-hoc comparisons in a two-way repeated-measures ANOVA in R

I need to analyse data from an experiment with two within-subjects factors, namely block (1, ...
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0answers
11 views

Finding Table of Standard Errors of Single Mean

I am using R to perform an anova analysis on model with a single factor (7 levels). I am interested in finding the table of means and standard errors for an balanced design. ...