1
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1answer
16 views

Mixed ANOVA post hoc analysis (and multiple comparisons)

I have a set of 12 subjects: 6 administred with drug A and 6 with drug B. For each subject two time-points have been collected (before and after drug treatment) for each analyte (over 6000). I had a ...
0
votes
1answer
40 views

Post-hoc tests for 2x2 ANOVAs (Type II & III) with interactions in R

I am trying to analyze data from an experiment using R and ran across a problem regarding the use of post-hoc tests with Type II & III ANOVAs. I only know of R functions that perform post-hoc ...
0
votes
3answers
35 views

Simulate data for 2 x 2 ANOVA with interaction

What is the best way to simulate ANOVA data for a 2 x 2 design with interaction using a regression approach? I want to generate the data so that I know the true regression coefficients of the model ...
0
votes
0answers
22 views

Preparing microarray data for batch effect detection by anova

I am working on a meta-analysis of clear-cell renal cell carcinoma data. The data are gene expression values obtained out of Affymetrix Human Genome U133 Plus 2.0 arrays. Currently, I am trying to ...
0
votes
1answer
47 views

Linear Regression In R and test of constant variance

I am trying to construct a regression model in R.I am getting an error while predicting the model. I am not sure if the newdata(which is my validation set) should be a data frame? ...
1
vote
1answer
18 views

Number of contrasts in an orthogonal contrast test

This is my first time asking a question here, so please let me know if anything is unclear. So I was trying to learn how to set up contrasts from this page, and here is the code: ...
1
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1answer
32 views

Interpreting output from anova() when using lm() as input [duplicate]

I am learning about building linear regression models by looking over someone elses R code. Here is the example data I am using: ...
0
votes
0answers
22 views

Building a linear mixed effects model?

Study Design I have a dependent variable (PP), collected under two different conditions (Condition) in ten subjects (Subject) of varying heights (Height), across three different trials (Trial). Both ...
0
votes
2answers
25 views

How to compare AR and ARIMA models?

Relatively new to stats. I use linear regression and get R^2, which is quite low. MODEL 1 lmoutar=lm(formula = ts_y ~ ts_y_lag + ts_x) So switched to arima ...
0
votes
0answers
39 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: ...
0
votes
1answer
34 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 ...
0
votes
1answer
40 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 ...
0
votes
1answer
48 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 ...
1
vote
1answer
57 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 | ...
3
votes
1answer
40 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) ...
1
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0answers
42 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 ...
0
votes
0answers
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 ...
0
votes
0answers
30 views

Understanding ANOVA formula in R and choosing the most appropriate model

I am new to R (and by extension statistics), and am having a tough time in making sense of this repeated measures ANOVA formula, please bear with me. I think I understand what the formula implies, but ...
1
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0answers
30 views

Partition of sums of squares (ANOVA)

Can anyone explain the theory (or the formula) about computing Sum Sq (bold highligh below) related to regression items? The Wikipedia link gives an introduction on how to calculate the total, model, ...
2
votes
0answers
69 views

In R, what does anova(f1, f2, f3) compare?

I'm trying to understand the reason why anova(f1, f2, f3) and anova(f1, f2) gives me different result while anova(f1, f2, f3) and anova(f2, f3) gives me the same. Here's the code: ...
1
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1answer
62 views

Why do ANOVA p and F values change?

I am currently conducting a two-way ANOVA on a dataset and have noticed how significance and F values change dependent on the type of ANOVA I use in R. Why is this? For instance, if I run a two-way ...
2
votes
0answers
47 views

How can I make 2-way ANOVA (Type I, II and III) with R?

I have the following data with factor 1 (A, B and C) and factor 2 (D and E): $$ \begin{array}{ccc} \hline & D & E\\ \hline A & 68 & 59\\ & 65 & 57\\ & 63 & 54\\ ...
0
votes
0answers
38 views

Analysis of repeated treatment design (Linear panel model vs. ANOVA)

General information Assume you have the following quasi-experimental repeated treatment design (T = Treatment, M = Measurement): ...
0
votes
1answer
62 views

ANOVA and finding differences between multiple groups over time

I was given a dataset to analyze with two factors, time and treatment, and one continuous dependent variable. Since the same individuals were measured at multiple times, technically it probably could ...
0
votes
0answers
14 views

ANOVA - comparing rows with replicates

I have a situation where I want to test for differences between rows and columns in my data frame: ...
0
votes
1answer
21 views

question on plotting error values for treatment effects from multiple regression output

Say I have some data, where a dependent variable, dv, is a function of some independent variable, iv, and a categorical ...
1
vote
1answer
61 views

Interpreting the ANOVA output for hierarchical linear regression

I followed this tutorial to learn Hierarchical Linear Regression (HLR) in R, but couldn't understand how to interpret its sample output of ...
1
vote
0answers
53 views

Using repeated measures anova: Am I right?

We have just finished an experiment, where we had samples distributed into 6 groups and each group receiving a different treatment. Each group had 5 samples, with 20 replicate measurements taken per ...
2
votes
1answer
39 views

R multcomp: contrasts for Tukey

I want to use the glht() function from package multcomp. In the linfct argument, I provide ...
1
vote
1answer
76 views

2x2 ANOVA, no main/interaction effects, post-hoc cell mean comparisons necessary/allowed?

I have a 2x2 between-subject design with unequal cell sizes. I ran an ANOVA with type I sums of squares to account for the unequal cell sizes. Neither of the two main effects nor the interaction ...
2
votes
0answers
37 views

Compare rows across columns - classic ANOVA?

I have a situation where I want to test for differences between rows and columns in my data frame: ...
1
vote
0answers
34 views

What is the equivalent of a repeated ANOVA using a mixed effect model with lme?

I have a data frame with this structure: ...
0
votes
0answers
26 views

Perform analysis of deviance on R/RPy aov() models

I am using stats.aov() in R to perform an ANOVA on my 2x2 within subject exeriment design. I am unsure how best to model the data so I have formulated 3 models, ...
1
vote
1answer
58 views

Two Way ANOVA repeated measurement

I am trying to compare the three replicate samples taken at different time point to see if the replicate one differ from replicate two and three and visa verse. My interest is to see if the three ...
0
votes
1answer
29 views

Repeated measures design with measurements from different groups of animals

In a repeated measured design we measure a particular variable at different time points from the same subjects. In animal experiments, if animals are sacrificed at every time point to measure a ...
0
votes
1answer
73 views

ANOVA and post-hoc analysis using R when we only have means and SD of three populations

I want to perform an ANOVA using R. I have three populations, represented by their respective means and SD: Pop.1: 5.5 +- 0.4 (n=100) Pop.2: 5.9 +- 0.3 (n=150) Pop.3: 6.2 +- 0.5 (n=200) Which is the ...
2
votes
1answer
149 views

anova type III test for a GLMM

I am fitting a glmer model in the lme4 R package. I'm looking for an anova table with p-value shown therein, but I cannot find ...
1
vote
0answers
43 views

Reporting two-way ANOVA

I've been trying to figure out how to properly report a two way ANOVA with two between-subject variables and their interaction. Most references I found suggest to report it in the following way: ...
0
votes
0answers
26 views

One Factor Repeated Measure, Two Way ANOVA

Is there some way in R to output not only the main effects and the interactions of the two factors using an aov() like function but also the variance of the subject within a non-repeated factor? For ...
1
vote
0answers
73 views

R - Post hoc comparisons in 2x2 ANOVA unequal sample sizes

I have a 2x2 between-subject design with (slightly) unequal cell sizes. Hence I chose to use the anova(lm(...)) function so that Type 1 SS are used: ...
0
votes
1answer
79 views

Why must one use ANOVA to interpret the impact of interaction effects and factor variables? [closed]

What is the purpose of the ANOVA table? I once learned that you can only interpret the significance (p-value) of a multi-level discrete variable, or an interaction effect using the ANOVA table. Why? ...
0
votes
0answers
16 views

Comparing F-values of covariates in R

I'm new here and have a question regarding ANOVA in R. I have an ANOVA table like this from running anova(model) in R, where ...
0
votes
0answers
321 views

One-way ANOVA with unequal sample sizes

I have a function for performing one-way ANOVA in R: ...
0
votes
1answer
32 views

Determine which group is more important

I have a question how to analyze mean differences where I am unsure whether I am lacking the statistical vocabulary or simply ignoring something important. I have a 5 point satisfaction variable ...
1
vote
0answers
143 views

ANOVA on percentages

Please read edit 3 first I am trying to find out the significant factors in a dataset of percentages, a sample of which are below. The difficulty is that the data violates the assumptions of ANOVA, ...
1
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2answers
143 views

inter vs intra group variance

Consider this example: ...
1
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0answers
69 views

lme vs lmer vs aov for three factor repeated measures design

I'm trying to run a tree-way repeated measures ANOVA on the following data: I have a completely balanced design with three within-subject factors (type, form and ch - channel) and one dependent ...
0
votes
1answer
37 views

Should we conduct post-hoc tests when there is a significant interaction but no significant main effects?

I have data showing outcomes of some treatment on different people grouped by sex and age (grouped into: infant, child, adult). I need to investigate if there is any difference in outcome among age ...
0
votes
2answers
108 views

Analysis using ANOVA

I want to compare 6 designs of spoons (D1,D2,D3,D4,D5,D6) in 20 children (blocks).I also want to see whether holding the spoon in right or left hand affects food-pinching response(number of M&M's ...
0
votes
2answers
407 views