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.

learn more… | top users | synonyms (1)

2
votes
0answers
9 views

MANOVA as protection against Type I errors

OK, so I have absolutely scoured the internet, and it appears that there is consensus (among people who really care about Type I error) that doing a MANOVA before doing multiple ANOVAs does nothing to ...
1
vote
0answers
9 views

Single-factor random effect ANOVA and components of variance

I've needed to learn some DOE for work and I've been going through Montgomery's book using R to help with the calculations. The fixed-effect models have been straightforward, but I have some trouble ...
1
vote
0answers
12 views

How to treat different (multiple) measurements on the same subject over time?

Let's say I am interested in some microscopic measurements on a subject, for example, the pore sizes on my hand. I want to see how putting my hand under a humidifier changes the pore size over time, ...
0
votes
0answers
10 views

Is there an accepted way to compare within all demographic categories (e.g., within males, within females, within whites, etc.) using MANOVA

I have three experimental groups (group A, group B, and group C), and gave all participants the same 50-question questionnaire. I then can run a MANOVA to determine if their responses (quantitative) ...
0
votes
0answers
29 views

Which statistical test should I use for my report which has Two sets of data?

I have collected data from load testing a website. The basic Idea here is that, a website hosting on a server is tested by increasing number of virtual users. Example, there are 5 iterations in each ...
0
votes
0answers
5 views

In an analysis of covariance table why do the sums of squares for the treatment, covariate and residual not add up to the total sum of squares?

I am trying to understand why this is the case, since in an analysis of variance table the sums of squares in the rows prior to the total row add up to the total sum of squares?
0
votes
1answer
23 views

Choosing the correct anova model

How does one choose the best model based on ANOVA's result? I mean I have 3 model outputs 1st is linear+all interaction, 2nd is linear+pair wise interaction and 3rd is linear and I am asked to choose ...
3
votes
1answer
28 views

Do I have to specify all main effects in a factorial ANOVA?

I am having an issue specifying main effects and interaction terms in an ANOVA model. The problem is, lets say that I have 3 factors, A,B and C. I am interested in the main effects of A, B but not C. ...
0
votes
0answers
25 views
0
votes
0answers
9 views

Allocation of product with ANOVA or something else (?) in R - what direction and tests to use?

Assuming a very simplified view of my data looks like this: ...
0
votes
0answers
20 views

Normalization before feature selection such as Fisher score (F-score)

The Fisher score (F-score) for feature selection is defined as in Combining SVMs with Various Feature Selection Strategies. However the paper doesn't mention any preprocessing to feature values such ...
1
vote
1answer
24 views

Multifactorial analysis of variance with repeated measurements-literature

What is the difference between multivariate and multifactor ANOVA? Does anybody have any pointers to downloadable literature about multifactorial analysis of variance with repeated measurements?
0
votes
1answer
22 views

Is it common practice to correct for multiple comparisons with multiple ANOVAs?

I gave three groups of participants (say groups A, B, and C) different treatments, then gave all groups the same questionnaire. The questionnaire has ~50 questions. I then run ANOVA on each of the ...
0
votes
0answers
11 views

Implementing ANOVA for a poisson distributed variable (count data)

I am currently working on a dataset that contains details on over 100k terrorist attacks. The variables of interest for each attack are attack type e.g. bombing (3 levels), country e.g. Iraq (5 ...
0
votes
1answer
17 views

nested paired tests

I have a design with patients treated with a certain drug.We have patient data before and after taking drug.Within in these patients there is are two types of people , responders and non responders in ...
1
vote
1answer
20 views

Interpretation of ANOVA main effect, ignoring one row

I'm reading a paper which performs a 3x2 ANOVA like so: ...
0
votes
0answers
35 views

Two-way ANOVA: error variance in numerator of F statistic for main effect

Let us consider a balanced two-way ANOVA without replications, having $m$ columns and $n$ rows. If we want to test the column effect, we use the statistic $F(c)=MS(c)/MS(e)$, where $MS(c)$ is the mean ...
0
votes
0answers
23 views

Fitting a GLM for binomial data in R

I am an R beginner and out of my depth! I am trying to build a model to analyse data regarding fertility in 2 populations of different levels of sexual selection(M and P), both of which have undergone ...
0
votes
0answers
19 views

What method is appropriate? - analysing patterns of attacks by region

I am currently working on a project using a dataset on global terrorist attacks. For each attack there are details on the type of attack which has 7 levels (e.g. bombing, assasination etc.), the ...
1
vote
2answers
44 views

ANOVA with three IVs

I have a following problem: I have some research data that need to be analysed. There are three randomized independent variables (binary) and one dependent variable (reaction time). The data consists ...
1
vote
0answers
42 views

Interpretation of residual plots — constant variance of residuals

I am trying to analyze these residual plots. Clearly, from the normal probability plot and histogram the standardized residuals are not normally distributed (it shows a moderate negative skew). ...
0
votes
0answers
22 views

Advice on ANOVA formula for nested random design

I have read "Design and Analysis of Experiments" 8th Edition by D.C. Montagomery. In Chapter 14, there is a nested experiment with two factor A and B. Both factors are random. Then the ANOVA test ...
-1
votes
0answers
37 views

Need advice on statistical analysis

I'm designing a study with 3 different groups that are to receive 3 different interventions for a set period of time (n = 100, month long interventions). Would this be called a randomized crossover ...
2
votes
3answers
58 views

Chi-squared vs ANOVA test

My study consists of three treatments. One treatment group has 8 people and the other two 11. Each person in the treatment group received three questions and I want to compare how many they answered ...
3
votes
0answers
49 views

Log Transformation

I am planning to run a 2x2x3 repeated measures ANOVA on reaction time data pre and post treatment. However, my data is skewed and I wanted to do a log transformation but have few questions. Can I ...
0
votes
0answers
14 views

Two Different Interaction Terms for Mixed Factorial ANOVA in R?

I have the following R output from a mixed factorial ANOVA: ...
0
votes
1answer
26 views

Significant omnibus f-test but planned comparison testing showing no evidence of effect

i'm testing the relationship between four age groups of teachers on their perceived level of job security. I've run an omnibus f-test on some data, 240 subjects- no examples of any skewness, and it ...
0
votes
0answers
12 views

BayesFactor Error Output in R

I am an R novice and I am trying to perform a Bayesian ANOVA (one-way) using R with the BayesFactor package. I want to test the null hypothesis that scores on a test do not differ between three groups ...
1
vote
1answer
26 views

Between subject post-hoc tests in an ANOVA with repeated measurements

I run an ANOVA with two factors A & B and repeated measurements. Now, I'm mostly interested in the interaction effect of the two factors A*B and would like to do some post-hoc tests in the form of ...
3
votes
0answers
22 views

Bound on the total change using Pearson's r

I am given an increasing series $(x_1,....x_n)$ and I know the pearson correlation between $(x_1,....x_n)$ and some (unknown) increasing series $(y_1,....y_n)$. Can I derive an upper and a lower ...
0
votes
0answers
8 views

Co-variance matrix and Factor graph representation

I have problem in fundamental understanding of factor graph representation: I am trying understand the relation between the Co-variance matrix and associated factor graph, of a Normally distributed ...
0
votes
1answer
34 views

How to use anova for two models comparison?

How should I understand the anova result when comparing two models? Example: ...
1
vote
1answer
26 views

Do I need to use a Bonferroni adjustment?

I am using three different ANOVAs to determine significance across two treatment levels. Because we only have two species I chose to run the same set of analyses for each of the species instead of ...
0
votes
1answer
14 views

Is F test used for feature selection only for features with numerical and continuous domain?

F statistic/test can be used for feature selection, e.g. from http://scikit-learn.org/stable/modules/generated/sklearn.feature_selection.f_classif.html#sklearn.feature_selection.f_classif ANOVA ...
1
vote
0answers
17 views

Analysis of pre-post data when 2 treatments given serially to same subjects

I have following data from a cross-over trial where subjects were given 2 types of treatments separated by a washout period. For each treatment measurement was made in pre and post treatment period. I ...
1
vote
1answer
25 views

Two way ANCOVA with slight heteroscedasticity

I am about to perform a 2-way ANCOVA but I reject the null hypothesis in Levene's Test with a p-value of 0.023. See standard deviation and sample sizes below. I googled up and down and found people ...
2
votes
2answers
24 views

If underpowered for three way interaction, but two way interaction is still ok?

I ran a three way 2x2x2 ANOVA (AxBxC) that turned out to be just shy off a significant three way interaction (p = 0.06). I ran the two way interactions for AxB for the 2 levels of C anyway. As it ...
0
votes
0answers
16 views

Losing power by doing repeated measure instead of standard anova

I have an experiment with one within subjects factor. It has 3 levels: sleep deprived (24 hours), sleep deprived (12 hours), not sleep deprived. Over the course of 6 weeks we run a counterbalanced ...
2
votes
1answer
23 views

Choosing between and properly interpreting Analysis of Variance vs Wilcoxon rank sum test

(Newb on this, so please assume good faith but low skill) I have this set of data where I'm interested in whether there is a significant and meaningful difference in ...
4
votes
0answers
68 views

Repeated measures ANOVA: what is the normality assumption?

I am confused about the normality assumption in repeated measures ANOVA. Specifically, I am wondering what kind of normality exactly should be satisfied. In reading the literature and the answers on ...
1
vote
0answers
17 views

Data Analysis Question from a Stats Novice (Hierarchical Multiple Regression and sample size assumptions)

I'm working on my dissertation and have only a very basic knowledge of stats. I am assuming all of you have a much better understanding and I need some clarification: I am comparing two groups ...
0
votes
1answer
34 views

One-way ANOVA on data with two factors

Assume there is no interaction effect in the data. However, it was gathered such that it had two factors. For example, let's say you look at running times of people from 3 different age categories. ...
2
votes
1answer
24 views

Does summary.aov() of MANOVA object adjust for multiple comparisons?

I performed a MANOVA analysis in R, testing if two populations differ based on their multivariate phenotype, comprising 16 measurements. I then used the summary.aov() function on the MANOVA model to ...
0
votes
1answer
27 views

2 factorial experiment (2 by 3). DV is NOT normally distributed

I just conducted an 2 factorial experiment that has 6 conditions (2 by 3). Specifically, my design is: IV1 = prior positive information (positive in A domain vs. control vs. positive in B domain) IV2 ...
0
votes
1answer
11 views

Additional T-Tests after Mixed-ANOVA required/ useful to test initial equalness of groups?

I am currently evaluating a mixed research design, where a treatment and a control group are evaluated over time. I am interested in the effectiveness of the treatment and therefore evaluate the ...
3
votes
1answer
38 views

Repeated measures ANOVA in retail sales programs?

I am studying the effects of a sales program on the weekly unit sales at ~1,000 retail locations. I am having trouble figuring out which statistical test is appropriate to run for this scenario. Here ...
1
vote
0answers
20 views

What to do when you have more than one column of dependent variable data?

I ran a 2x2x2 mixed Anova on my data I have only got a significant result for one factor and also a 3-way interaction. Trying to find out where the significance lies in the 3 way interaction at the ...
0
votes
0answers
16 views

Is it possible to get contradicting conclusions when conducting ANOVA?

I was given a set of data and asked to perform a test for existence of regression, as well as to calculate a value for the coefficient of determination and interpret whether the linear model is useful ...
3
votes
2answers
64 views

ANCOVA intercepts - does R center data?

I have 2 fixed effects and 2 continuous predictors. Nothing interacts so I believe I want a model of the form: $$Y_{ij} = \mu + \tau_i + \beta_j + \gamma_1(X_{1ij}-\bar{X_1}) + ...
0
votes
0answers
17 views

R anova (aov) repeated measures gives same effect in different error sources

I have a repeated measures design, where A and B are within-subjects factors. I tried m1 <- aov(y ~ A * B + Error(subject/(A*B))) summary(m1) But the results ...