All Questions
33 questions
1
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1
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161
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How to code a lme, lmer, or glmer model for a split-plot design (ANOVA)?
I have a study where the initial height of seedlings were measured at year 0 and again 11 years after treatments were applied and a net change in height was recorded.
I have a split-plot design as ...
- 13
2
votes
0
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108
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How to conduct repeated measures Anova when there are two within factors but I am only interested in the effect of one factor?
For example, if my experimental design requires the subjects to participate in two identical sessions at two different time points(factor 1). In each session, the subjects go through all three ...
- 21
0
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0
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42
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How to best interpret factorial design results?
I am analysing data from a 2^3 factorial design in R. I am using blocking, and I was wondering if my reasoning is correct. I am testing reaction time in milliseconds with three factors (Type of test, ...
0
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0
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194
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Is there a function in R to give the lack of fit and pure error of an ANOVA completed on a half 2^k factorial with centre points?
I have a half fraction factorial experiment for four factors, meaning I have eight experiments that I conduct. I expect that some of the responses are quadratic and not linear, thus I included centre ...
0
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2
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814
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Two way ANOVA unbalanced and nested TYPE III. Significant results
I have an unbalanced design with nested factors. In particular, the nested factor is obesity, with levels: of obese and nonobese. The other factor is group: women with syndrome, control women, and ...
1
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0
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168
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2x2 Repeated measures ANOVA gives DIFFERENT result in R and SPSS? (Same type of sums/data/analysis) Anyone know why?
Reposting this because I fixed the formatting to see if someone can actually provide a solution for this problem. I have a study design in which I am carrying out a 2x2 repeated measures ANOVA in ...
- 58
0
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1
answer
553
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Analysis of design of experiments with binary response
Having a hard time determining the best way to analyze this DOE, as I'm generally used to outputs in a different format and with numeric responses.
I've essentially got 2 variables at 3 levels and a ...
0
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1
answer
3k
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Two factor ANOVA with blocking
I am conducting an RCBD experiment in which I have Treatment A (with 5 levels) and Treatment B (two levels). It is also being done in 3 separate locations (3 blocks). My question is, how can I do the ...
- 3
1
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0
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25
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How to evaluate the interaction between 3 factors with a single observation in each cell?
Some context: An experiment was conducted to evaluate the interaction between 3 factors in the removal of a contaminant from water. The selected factors were:
Coagulant: a chemical substance to ...
4
votes
3
answers
12k
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Why do I not get a p-value and F value from ANOVA in R?
I am asked to determine using an appropriate test whether the internal concentration of isoleucine is statistically different between appropriate experiments. So I constructed a data frame in R as ...
- 41
3
votes
1
answer
55
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What statistical tests should be performed to test effect of trials on response times where each subject has different number of data-points?
I am running a behavioral experiment where a number of subjects (=20 in my case) perform a simple cognitive task. The experiment consists of a fixed number of trials (say, 40 in my case). During each ...
- 428
1
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0
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53
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How to analyze repeated measures when condition changes at each time point?
I have a dataset from a repeated measures experiment that I am trying to analyze. The experiment had 4 possible conditions. Participants were measured on 1 condition and then again on a second ...
- 11
3
votes
2
answers
1k
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Randomized Complete Block Design with Replicates
A horticulturalist conducted a nitrogen fertility experiment for lettuce in a randomized complete
block design. Five rates of ammonium nitrate treatments (0, 50, 100, 150 and 250 lb/acre) were
...
- 443
4
votes
2
answers
786
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How do I analyze a three factor ANOVA without replication in R?
This summer, I conducted a growth chamber experiment testing the effects of the projected climate change conditions on the growth and survival of newly germinated seedlings of Acadian forest tree ...
- 41
5
votes
1
answer
455
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Randomized Block Design Models
I have been asked to fit the following models in R:
The models are based on this data:
I know the mediums are the blocks and the units of the active ingredient are the treatments. I understand how ...
- 63
3
votes
1
answer
211
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Is it correct to run a mixed model (2-ways anova) on a unbalanced and incomplete design?
I am studying the effect of land use on biomass. I am struggling to find the right model to correctly analyse my data.
Data description
I have surveyed land use changes in 20 fields for 3 years. I ...
- 163
1
vote
1
answer
806
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Performing repeated measures ANOVA on unstacked data in R
I am trying to do a repeated measures ANOVA on unstacked data for my experiment. For background, my experimental design is as follows: I have 160 stimuli divided evenly into 8 counterbalanced list, ...
4
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0
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190
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Why there is no agrement on power / sample size for factorial repeated measures design?
I'm not really sure to what degree this is a statistical question but thought this might be the best place to start. If my questions prove only my ignorance please vote it down and I'll delete the ...
- 557
1
vote
1
answer
96
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Which anova model is the correct one (R)?
I have measured running times with 4 different systems (1 gold standard) and 4 different running styles.
Every run was carried out by 6 athletes, who were measured by all systems simultaneously.
Now ...
- 13
1
vote
1
answer
1k
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Cells means model in R for unbalanced Latin square design
I used a 4 x 4 Latin square experimental design recently and have been advised that a cell means - rather than sum of squares - approach is more appropriate because I have an unequal number of ...
- 153
3
votes
1
answer
3k
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Incomplete block design analysis / design with R
I have a few questions that arose when working on designing the following experiment. The numbers and variable levels are all made up for examples sake.
I want to test the effect of incubation period ...
- 33
2
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1
answer
136
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Which ANOVA test to use in this experimental design?
I have an experimental design as follows:
Three groups of cakes: treatment A, treatment B, control;
Three replicates per cake.
They are observed during 10 days for microbial growth.
My interest is ...
- 133
2
votes
1
answer
254
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In a factorial experimental design model, does it make sense to remove statistically insignificant factors?
I am trying to analyze data from a factorial design experiment with three factors: Nitrogen, Phosphorus and CO2, with 2 levels each. I ran a three-way ANOVA in R:
...
- 202
3
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0
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345
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True replicates or nested data ANOVA - only one experimental unit per condition
I'm in materials science. I have a fractional factorial experiment. I am investigating the main effect of various treatments on a measured response. The exact details are probably not needed to ...
- 31
1
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1
answer
947
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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 ...
- 123
3
votes
3
answers
9k
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2x2 experimental design: t-tests vs. mixed anova analysis
I have conducted an experimental study, with 1 within-variable (time: T1 and T2) and 1 between-variable (group: control and treatment), measuring just one dependent variable.
I understand that this ...
- 141
3
votes
1
answer
181
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How to define a between variable is random effect in Anova in R? [closed]
I am using 'Anova' function in 'car' package to analyze plot - split experimental data.
I have 1 between group, and 2 within group variables, so it is SPFp.qr analysis.
The problem is, the between ...
- 1,017
1
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0
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165
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Why does aov consider a 3x3 factorial design unbalanced?
I have a two factor, bot at 3 levels with all factor levels, and with 5 replicates for each. This is a standard 3^2 factorial design, and yet aov gives the message "Estimated effects may be unbalanced"...
1
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2
answers
283
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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 ...
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5
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1
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3k
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What does R mean by "unbalanced design"?
I think this means an unequal sample in different conditions. But it seems to mean something else. . .
I have a data set like below
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- 512
3
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2
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541
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Partial, adjusted or Type-III SS of factorial experiment in R
The partial SS for two factor (N and P factors) factorial experiment with interaction can be calculated as:
\begin{eqnarray*}
\textrm{SS}\left(N_{i}|\mu,P_{j},\left(NP\right)_{ij}\right) & = &...
- 2,759
6
votes
2
answers
7k
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Random block design ANOVA in R
Quick question: I have found this tutorial which recommends a two-factorial design for the following setup: three menu items (fixed factor) are tested in six restaurants (random factor). The guide ...
- 7,697
3
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0
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871
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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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