All Questions
Tagged with anova experiment-design
280 questions
1
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multi factor anova when only one factor is controllable and the others are not
Using an example of baking a crepe cake, assume that there are 3 layers to the cake, with each layer having 3 flavors. The bakery then assigns three bakers, one to each layer. The goal is to ...
- 251
2
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2
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456
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Calculating the degrees of freedom
Hi I wonder if there is a standard way to calculate the degrees of freedom. I am having a hard time understanding why these sums of squares has only one degree of freedom.
In one-way ANOVA (one ...
- 167
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 ...
0
votes
1
answer
151
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Making sense of an actual equation obtained after Box-Cox transformation
I have recently performed and analysed an experiment and I am currently stuck on making sense of the outcome. Any help would be much appreciated.
The experiment consists of a simple DC voltage source ...
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4
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3
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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 ...
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1
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0
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34
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Analysis of variance in a multi-site agricultural field experiment?
I have a dataset on the yield of rice collected from 17 different sites where 3 different fertilizer management methods were tested.
However, there were three different rice varieties tested in an ...
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2
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1
answer
49
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ANOVA and independent samples
Let's say there is an experiment of determining the best cookie recipe with 4 categorical factors. There are $S$ subjects that eat and rate cookies made using $R$ different recipes. There are $R$ ...
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0
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0
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36
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analyze / model the difference between experiment and control group
In an experiment with experiment vs control groups, how to train model to explain the different results between experiment and control group (ie, has treatment vs no treatment)?
Eg, customer ...
- 173
2
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1
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116
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Determine the variabilty of the volume given the length, width and height
I am to solve a problem where I am given the mean value, $\mu_i$ and variance, $\sigma^2_i$ where $i\in{L,W,H}$ which represents the Length, Widht and Height related variables respectively.
The ...
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2
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1
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61
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Questions about Data Analysis [closed]
For my research I'm examining whether applying a certain promotional intervention improves the amount of misshapen products bought. The study contains of two parts. In part 1 Scanner data from ...
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4
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1
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704
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Analyzing clustered (repeated measures) data with very few clusters
What is the most appropriate method for analyzing clustered data (i.e., repeated measurements nested within subjects) when there are very few clusters (e.g., 3 subjects)?
Here's a brief description of ...
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1
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0
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40
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Variance of effects in $2^kr$ factorial design
I'm working through The Art of Computer Systems Performance Analysis, a statistics book focused on analyzing computer performance, and I don't follow the logic for computing the variation of effects ...
- 111
1
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0
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23
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Adequate statistical method to compare objective measure vs estimations
I am using a software for image recognition to do the following:
calculate the percentage of a surface that is painted black.
On the other hand, there are several observers that estimate the ...
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3
votes
0
answers
269
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Two-way ANOVA/GLM for 2x3 incomplete factorial design
I am designing a within-group study with two factors (fixed novelty, levels: old, new; and indexical novelty, levels: veridical, statistical, new; so a 2x3). Now, ideally, I would just cross these ...
- 31
3
votes
1
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2k
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How to calculate sample size for blocked-design two-way ANOVA?
Does anyone know of a good online calculator or at least a good paper that details how to calculate the needed sample size for a blocked-design two-way ANOVA experiment? I've seen a ton of references ...
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1
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0
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47
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What statistical test is needed for this experiment? Is it a simple t-test?
Suppose I have data which is something like the table below, where I measure how an individual does on a task under 4 conditions. So we observe A, B, C, D for a given individual. There are $N$ ...
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1
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1
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84
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What statistical test is appropriate for the following experimental design, apart from mixed two-way ANOVA?
We are planning a study of the effectiveness of two therapies for treating depression. Group A will receive the current therapy and group B will receive a new and improved therapy. Participants are ...
2
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1
answer
123
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experimental design - repeated measures within factor combinations?
Sorry for what might be an obvious question, but I have a question about an experimental design for which I can create a "mouse" analogue:
I have 270 mice. I have 2 treatments (factors)-- L ...
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1
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0
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174
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How to handle strong ceiling effects in an repeated measurment experiment?
i am trying to analyse some old data.
It's an between-within subject experiment with 4 experimental conditions and 2 points of measurment.
The question is, if there are differences in effect of the ...
- 76
1
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3
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587
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ANOVA complete block design, more units per block than treatments
I would like to design a randomized complete block design experiment (RCBD). Let's say I have 3 treatments and 10 logical groupings of my experimental units (EUs) which are the blocks. If each of my ...
- 497
1
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1
answer
75
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Between-subject design and within-subject anlyses
I have a between-subject design in which there are two groups (A, B) and two conditions (x, y). I ran an ANOVA and found no interaction whatsoever and no significant differences in the two conditions.
...
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1
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0
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224
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Is it possible to affirm there is pseudoreplication in a design without making assumption on variable importance?
this is quite an abstract question, but I am trying to learn more of the basics in pseudoreplication.
Pseudo replication is defined by Hurlbert (1984) as:
Pseudoreplication may be defined , in ...
- 539
3
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1
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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 ...
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1
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0
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53
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Is there value in assigning a dimension-specific weighting when calculating the main effect?
I've been looking into factorial designs and noticed an interesting property. Is this simply a mathematical trick or can we attribute some 'meaning' to it?
Say we have a $2^k$ design where k = 3 here....
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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 ...
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1
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0
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26
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Best approach for maximising power?
This seems like a relatively very simple question compared to the apparent complexity on this forum.
I'm putting my PhD method together, within-subjects experimental design (counter-balanced related ...
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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
2
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1
answer
480
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Block-treatment interaction for Randomized Block Design (RCBD) and Generalized Random Block Design (GRBD)
I understand that RCBD experiments usually only contain one observation per cell (block-treatment combination). Also, there should be no interaction between the treatments and blocks.
In GRBD, there ...
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1
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0
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284
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How to code a two-way ANOVA with split-plot design using R? [closed]
I am analyzing a split-plot land-use experiment and I am stuck on the R code.
We used four sites and on each site the following design:
We conducted a full-factorial design with two factors (land-...
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3
votes
0
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95
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ANOVA/ANCOVA - how to analyse
In a basic research design where you want to test how some intervention (let's say our IV is 'drinking' with the categories
water;
sprite; and
rum)
affects some continuous measurement (let's say ...
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1
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0
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58
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Split plot with RBCD in R: Are inferences valid when output reports some effects are not estimable?
Data are from an agricultural experiment and are the proportion of turnips damaged by cabbage maggot in different insecticide treatments (note preliminary investigation suggested data were ...
- 11
4
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2
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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 ...
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1
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0
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39
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What is the design of this experiment and how do I analyze it? [closed]
I carried out an experiment in two locations. For the two locations, the experimental set up was 95 genotypes of a plant in 3 replicates. For each replicate, I had 3 blocks in which the genotypes were ...
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4
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1
answer
760
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Unequal variance in randomized experiments to compare treatment with control?
Consider a randomized experiment to compare (one or more) treatment(s) with a control. Since groups are defined by random assignment, we should expect equal variances for a null-experiment (that is, ...
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0
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1
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84
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How to study a fractional factorial design? [closed]
I wonder why a DoE/fractional factorial design isn't studied with the help of a linear mixed model? Or an Anova?
How to analyze it in general is e.g. given here.
Background: I will study several gas ...
- 3,493
1
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0
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106
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Does ordinal logistic regression substitute for "multifactorial Friedman test"?
I'm searching for an appropriate statistical test, more or less a multifactorial version of Friedman test. But I'm also wondering if Wilcoxons rank sum test can do the job.
Experimental design:
10 ...
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2
votes
1
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141
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The Relationship Between Experimental Design and Non-linearity
It's well known that the classical ANOVA (and ANCOVA) experimental design techniques can be expressed as linear regression (with categorical factors). However, linear regression is just that – it ...
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0
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1
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57
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I cannot decide which test to use for my experimental design - 2-Way ANOVA?
My experimental design consists of 6 treatments, each of which are measured Before and After a particular application. I want to see if there is any difference between treatments both Before and After ...
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1
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0
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26
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"Incomplete Design" Problem: 2(between) x 2(within) x 2(within--but only in one between group!)
Problem:
I am trying to analyze an experiment with the design in the title:
2(between) x 2(within) x 2(within--but only manipulated in one group)
My initial hunch was to run two separate 2 (between)...
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0
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0
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343
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Can you conduct contrast analyses when interaction effect is non-significant?
I ran a 2 (factor A: A1 vs. A2) X 2 (factor B: B1 vs. B2) between-subjects design experiment.
I had an a priori prediction that the effect of factor B (i.e. the difference between B1 vs. B2) would ...
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0
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0
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19
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Comparing means between 3 different groups across time (given that the 3 groups are defined by 2 factors)
I have 3 different experimental groups:
1) Wild-type, control
2) Transgenic, control
3) Transgenic, Drug-treated
Therefore, my groups are defined based on two factors: genotype and drug treatment
...
2
votes
1
answer
33
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which experimental design better fits?
I test the effect of a plant dose on the abundance of a specific microbe, cultured in glass tube in vitro. The treatment consist of 5 doses (0, 1, 2, 3, 4). Each culture tube receives one of the dose ...
0
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0
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23
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Interpreting ANOVA results in the educational context
I have run an experiment in a six-week course to measure the effect of my educational treatment on student engagement. The treatment happens on weeks 4 and 6 of the course (for all of the students) ...
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2
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0
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555
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4 x 4 x 4 Factorial Design or 4 x 4 Factorial with Blocking?
Problem here: https://i.sstatic.net/eIzLh.jpg
I was thinking that this problem might just be a 3-factor factorial design, since obviously the ad campaign and packaging are factors (we're interested ...
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5
votes
1
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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
2
votes
1
answer
531
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ANOVA with Error term
I am looking for help to create a model for the following data:
I'd like to understand if the abundance of a certain microbial group (dependent continuous variable QUANTITY) found in soils is been ...
- 23
0
votes
2
answers
204
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Multiple comparison problem
If I conduct 19 tests (e.g. 19 pairwise comparisons of treatment means in an experiment), what is the probability that I will find at least one P value < 0.05 due to chance alone? With number of ...
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1
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1
answer
75
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Factor importance in multivariate experiment
I'm trying to analyze a multivariate experiment and show impact of each factor in a multivariate experiment. The general way to do this analysis would be to perform ANOVA:
...
- 253
1
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1
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165
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When to use blocks?
I am currently studying Random Complete Block Designs (RCBD) and I would like to ask a question.
I cam across an example where we were able to conclude with the RCBD as significant, but regular ANOVA ...
- 113
1
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2
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2k
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Split split plot ANOVA table: r = replicate or block?
I have seen various ANOVA tables for analysis of split split plot designs, and some have the first term ''r'' defined as the block while others have it as the replicate. This is confusing to me, as ...
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