Questions tagged [blocking]
In the design of experiments, blocking refers to grouping similar experimental units together in groups ("blocks"). Comparing treatments based on within-block differences reduces the influence of extraneous variables, thus increasing power.
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Experimental design with two factorial treatment and blocks of the treatment combination
I am going to do an experiment with planting seeds involving 2 factorial treatments. There are 4 families of seeds: F1, F2, F3, F4 and 3 foliar seed treatments: T1, T2, T3. There will be 160 seeds for ...
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To pool controls or not?
I have a data set containing measurements from cells that have had 200 different perturbations applied to them. Each perturbation has been applied in duplicate. Because there are so many perturbations,...
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Understanding the advantages of CRD experiments
I am self studying an introductory course on Designed Experiments and have come across the notion of a Completely Randomised Design (CRD) defined as follows:
Completely Randomised Design: the ...
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Relationship between blocks, factors and treatments
I have recently began studying a course on Designed Experiments and am having some trouble understanding some of the terminology. I've looked at some other answers on the site and I think that I am ...
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Between subject design, spread over multiple days
We have a between subjects design, testing for the impact of aesthetics on occupant satisfaction. Intervention is carpets vs no carpets.
The people participating in each leg (intervention vs control) ...
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Split-plot design analysis by Linear Mixed Models in R
I am trying to analyse data from a Split-Plot experiment by Linear Mixed Models with lme4 in R. The design consists of a whole-plot factor and two split-plot factors (see attached layout). Whole-plot ...
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Blocking Design
Ran an experiment whereby I had a factor of 5 different levels on a plant cultivar. A wide range of responses were recorded. Due to the layout of the room, I quickly realised that blocking was ...
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Necessary and sufficient condition for existence of balanced incomplete block design
State and prove the necessary and sufficient condition for an incomplete block design to be balanced
A balanced incomplete block design (BIBD) is an incomplete block design in which
b blocks have ...
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Is it okay to block by two similar variables in a simple ANOVA, where one contains the other?
My friend and I had a disagreement about some experiments in an entry-level statistics course. The experiments used human subjects with each participant doing several run-throughs, and so in the ...
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Difference between blocking and split plot-design?
What is the difference between blocking in an experiment design and a split plot design?
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How to use optFederov() and others for DoE?
As a follow up on DOE for evaluating a factor with more than 2 levels I would like to address some questions:
How do I determine the number of trials (in general and for a fractional design)?
Which ...
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Balanced incomplete block design - randomizing treatment order
In a balanced incomplete block (BIB) design, what is the best way to ensure each treatment appears in all positions/orders? Should I randomize treatment order within each block, so that participants ...
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difference between stratification and blocking in experimental design
What is the difference between stratification and blocking in experimental design(or randomized control trial)?
Blocking is to obtain homogeneity in a controlled factor. However, I can block more than ...
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Design of Experiment for one factor in R [closed]
Is there an package to design an experiment with a single factor, potentially with multiple levels?
I want to know how a certain voltage depends on temperature and for that I initially planned to ...
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Possibility of non-binary balanced incomplete block design
Balanced Incomplete Block Design (BIBD) is defined to be a block design which is proper, equireplicate, incomplete and binary such that every distinct pair of treatments appear together $\lambda$ ...
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Blocking in $3^2$ fractional replicated design of experiments
I'm new to design of experiments and I'm planning an experiment which involves 2 factors at 3 levels ($3^2$ design). I'm using 3 levels as I think that there will be some non linearity, but I cannot ...
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Doing repeated measure with blocking design
for this study which analysis do you suggest? repeated measure or blocking design?
I have 6 subject, to compare effect of a drug administered in four dose levels. Dose 0 we used control. two days wash ...
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How to calculate how many levels of nuisance factor I need for a desired power level in my experiment
I have a nuisance factor that introduces a lot of variation in my data. I want to know how many levels of this factor I need to include in my blocked design to get a power level of, say, 90%.
As an ...
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Unbiased Estimator for Mean Response to Treatment
$\newcommand{\eps}{\varepsilon}\newcommand{\szdp}[1]{\!\left(#1\right)}$
Problem Statement: Consider the following model for the responses measured in a randomized block design containing $b$ blocks ...
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Why is it acceptable to use the Sum of Squares of an Interaction as the Sum of Squares Error in a Randomized Complete Block Design?
Take for example the RCB design [Y = I + B + F + E], where...
Y is the response
I is the overall intercept
B is a blocking factor with two levels
F is a treatment factor with two levels
E represents ...
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How to analyze a randomized complete block design (block, plot, year) when assumptions of normality and heteroscedasticity are violated?
How do you analyze a randomized complete block design (6 plots within 4 blocks, data collected over three years) when assumptions of normality and heteroscedasticity are violated?
Is this correct? Use ...
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Is it possible to conduct meta-analysis for interaction between two continuous variables
all.
I have conducted four studies to examine an 2-way interaction predicting a continuous outcome variable from a continuous independent variables and a continuous moderator. So everything is ...
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One factor with two levels with random group effect
I'm testing the hypothesis: prey exposed to the chemical cues of a predator will have lower feeding rates than prey feeding without predator chemical cues.
In this simple food chain the top predator ...
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Is it acceptable to remove a block of data from an experiment due to outliers
I performed an analysis a while ago, and the experiment was blocked for production day (3 different production days). Two of the production days had terrible outliers, and after looking at the Cook's ...
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Ex-post grouping blocks, when analyzing blocked randomization experiment, to avoid $N_b=1$ blocks
In an experiment I conducted, randomization was stratified geographically and then blocked by the baseline outcome variable, $x$. That is, within each strata, $s$, I grouped observations into blocks, $...
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3 Treatment Agronomic Experiment: Latin Square or Randomized Complete Block Design with 4 replicates?
I need help with designing an experiment. Suppose I am testing 2 fertility programs against a control in Lettuce, for a total of 3 groups (Program A, Program B, and Untreated Control). Let's assume ...
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Treatment combinations in different blocks for a $2^6$ design with partial confounding
Let us consider a $2^6$ design in 8 blocks with ABCD, BCE and ADEF as independent effects are chosen to be confounded with blocks.
Q.1 $\:$ Write down the treatment combinations in the principal ...
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Change parameters block-wise in experiment design?
Is it possible to generate an experiment design which changes a parameter block-wise?
To be more precise what I would like to do:
Run an experiment with a certain parameter (humidity) fixed which is ...
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Block design or completely randomized?
I have 5 conditions in my experiment: A,B,C,D,E and my sample size is 200 subjects.
I want to have 40 subjects per condition, so I assign a condition to a person randomly without replacement.
E.g. ...
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Experimental Design Problem with Goofy Constraints
I am having trouble designing an experiment. I will give a hypothetical example that shares the main features of my actual problem.
Suppose there are:
$M$ meadows, indexed by $m={1,...,M}$, where $M \...
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The treatments are collectively not significant but one of the treatment is significant
I am confused to interpret this kind of data.
The Avg_Treatment is collectively not significant since the P-value is 0.094, bigger than the significance level 0.05....
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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 ...
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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 ...
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Does RCBD tend to increase the F value compared to the one way ANOVA?
I thought that the RCBD model accounts for the variation from different factors, and so when we use ANOVA, the treatment effect gets "muddled up". Hence our F value in the RCBD model is higher than ...
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Randomised Block Design
Suppose the response of three different treatments, $A$, $B$ and $C$ are measured in two different hospitals of a country. The data are given below.
My question is: so far I understand it is a ...
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Determining standard error of the mean from a correlated, stationary time series using known autocorrelation without block averaging
I'd like to determine the SEM of measurements taken from a stationary time series. SEM calculation using all measurements isn't accurate because adjacent measurements may be highly correlated, so the ...
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What statistical test (using R) can reveal relationships between 5 factors in randomized block design?
I'm at a loss as to how I can efficiently obtain p-values in R for the relationships I am interested in exploring in my dataset.
Here is a picture summarizing the block design.
Various response ...
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Analysis of incomplete block design and block-level attributes
I am working in a system where experimental treatments are necessarily associated with specific blocks (a complete design is not possible) and am looking for guidance on valid model specification.
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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
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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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Do I want a mixed model for fractional factorial designs?
I have created a D-efficient fractional factorial design of 48 combinations from a total of 192 possible combinations (4x2x2x3x2x2).
For the experiment, I plan to have 4 runs in 12 blocks and 40 ...
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Blocking vs. Control
Am I thinking about this correctly?
Blocking is something that is done on the experimental design level: If I'm not interested in the differences between school districts, I block by school district ...
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appropriate error term for a randomized complete block design, possible split plot in time, with subsamples (in SAS PROC MIXED))
I am analyzing the results of an agricultural experiment, as follows:
Plots are laid out in a randomized complete block design with 3 replications. They have been either conventionally or organically ...
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Why is ABC interaction completely confounded in this factorial experiment?
Consider a 2^3 factorial design layed out in 2 blocks ,with plot size 4, as follows
Block I: {1,ab,ac,bc}
Block II: {a,b,c,abc}
This is replicated four times.
abc is said to be completely confounded ...
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Identifying treatments with non-zero effects
I have a complete block design experiment with a large number of treatments were I am trying to identify treatments with significant effects (positive or negative). I know the Friedman/Durbin tests ...
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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 ...
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4 x 4 x 4 Factorial Design or 4 x 4 Factorial with Blocking?
Problem here: https://imgur.com/Nl8AWie
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 in ...
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Crew selection: ranking rowers by letting them race against each other
Seat selection is a common practice in competitive rowing and I would be curious about more solid statistical underpinnings: there are more rowers in a team than the 8 seats in the crew boat. So the ...
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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 ...
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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 ...
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