The design of experiments (DOE) is the study of how to structure an information-gathering exercise where variation is present. In statistics, controlled experiments are usually implied, meaning that study units are randomly assigned to conditions where levels of a variable have been independently ...

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Repeated measures anova in R

I have a dataset containing percentage scores for 15 participants. There are two observations for every participant, one with an intervention and one with a placebo in a double-blind design. Each ...
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28 views

How to deal with statistically insignificant factors?

I used $2^4$ factorial design to screen significance of the factors $A$, $B$, $C$ and $D$. It turned out that $A$ and $B$ were significant, whereas $C$ and $D$ were not. Since there is no need to ...
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Expanding an experimental design

I have completed test work following a randomised response surface (multi-factor) experimental design (Central Composite Full) but have found that my levels for two of the factors are not broad ...
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Number of model terms and nTrials in optMonteCarlo from AlgDesign R package [closed]

I am learning about optimal designs with AlgDesign R package and trying to understand a relation between the number of model terms and nTrials in optMonteCarlo. An example model has 5 factors with 2 ...
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29 views

How to measure extraneous and confounding variables?

The test-re/post/test methodology entails establishing a baseline, introducing a condition and measuring the effect size. The condition is known. But whether or not it yielded some changes, is what ...
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single run analysis of all characters in a diallel analysis [closed]

i need to do diallel for all traits PLHT,EHT,DT,DS,DM,KR,KR/ROW,EL,ED,GRAIN YIELD,FODDER YIELD,100KW for maize trial data in a single command.whether it is possible in R stattistic and how i can put ...
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Designing paired samples of Group A vs. Group B+C

I have decided to use a strict bioinformatics algorithms that under its way calculate fishers exact test. My samples are to parentals A1 and A2. These were treated and subgrouped into 14 clones. Two ...
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What family of GLM when response is Bray-Curtis dissimilarity? Should I use “adonis” instead?

I have some questions about testing for effects of different experimental levels on community similarity. I'll explain my planned experimental design before I ask the questions: I have two methods ...
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General strategy of confounding design

Example: Suggest a confouding scheme for a $2^8$ experiment in 16 blocks of 16, assuming that all 2-factor and 3-factor interactions are to be estimated. Please find the confounding design. Question: ...
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6 views

Completly Randomized Trials versus Incomplete Cubic Lattice

I have a 2x2x2x2 design, which I wish to balance. Previously, the binary factors appeared throughout the experiment with a 50% probability, which each have to result in a uniform distribution. I am ...
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sample size for multi-arm randomised control trial measured over time

I would really appreciate any advice on calculating a sample size: This study involves looking at a specific disease, then performing a randomised control trial in two different geographical areas ...
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27 views

What is the relationship between LATE and TOT?

My understanding of LATE was that it was the effect of a treatment on individuals who were induced to be treated by the experiment. That is, the effect on compliers. My understanding of ...
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How to aggregate many simulation runs for curve-fitting?

I have results from about 200 runs of a simulation model. The results contain a stochastic response variable which I want to approximate with a curve-fitting approach. So far, I have opted for ...
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4 views

Power analysis for two-sided non-compliance

Using Chamber of Commerce data for a small town, a local non-profit wants to evaluate the effectiveness of direct mail vs. email for getting business owners to contact the non-profit. We aren't ...
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1answer
34 views

Does descriptive research have dependent varibles?

I am doing a research proposal for a descriptive study to identify the health beliefs and perceptions among women to mammography breast cancer screening. I am using a Likert scale that is divided into ...
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1answer
29 views

Why does R power.prop.test & R prop.test show inconsistent results?

I am a bit confused by the differences I am seeing between R's power.prop.test & prop.test functions. To estimate the sample size needed for an A/B test I am conducting I am using the following ...
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18 views

How do I test the parametric assumptions of a split-plot ANOVA?

I have an RCBD split-plot experimental design for testing the effects of drought, tillage, and nutrients on plant biomass: Block = random factor (2 blocks of 10 plots each, total 20 plots) Drought = ...
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Do I still need ergodicity if I have multiple/infinite time series of the same data generating process?

The main reason we need ergodicity (and therefore stationarity) is, as Shalizi puts it: The ergodic theorem is important, because it tells us that a single long time series becomes ...
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Nested mixed experimental design with crossed factors for laboratory validation procedure: how to model it?

I have been asked to analyze the following laboratory experiment: 14 donors’ red blood cell samples are typed for rare antigen-asset recognition by an automated procedure (machine), which returns a ...
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39 views

the Randomised Complete Block Design

I got the following output using the Randomised Complete Block Design: ...
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One-way Fixed model

Duppose we have 12 treatments, and to start the experiment we choose these treatments, randomly. However, after selecting one treatment, all the samples are gathered and we shift to the next treatment ...
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42 views

What is my study design

I have two sample groups and I will not be manipulating the participants in any way so this is not an experimental design. However I wish to compare the results of the two samples (between subject ...
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1answer
17 views

What is the proper way to increase power when randomizing at the village level?

Let's say that we have a hypothetical RCT with the following information: --We are interested in seeing whether a particular belief held among some individuals in a developing country can be ...
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Pros and cons of various designs

Help me with this question. I'm clueless. CROSSOVER DESIGN PROS- Gain in precision- compare approaches within students, so variation between students is eliminated. CONS- Susceptible to carry-over ...
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How to correctly analyzed a mixed within-subjects/between-subjects design?

I recently ran a perceptual study in which I aimed to measure how emotion recognition accuracy from whole-body motions changed when two type of body representations were used. Five actors Ai with ...
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Confounding variable that is the focus of experiment

The wiki defines confounding variable as an extraneous variable in a statistical model that correlates (directly or inversely) with both the dependent variable and the independent variable ...
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1answer
27 views

Ranking Data Comparison

I'm currently analyzing my experimental data and I have a question about comparing two variables. In the experiment I have a question which asks respondents to rank a set of pictures based on their ...
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40 views

When is there a point for using regression with controls to analyze experimental data?

Many randomized controlled trials in economics (and probably other sciences as well?) use regressions to analyze data obtained from experiments. In the simplest setup with binary treatment, assuming a ...
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Why use Coded Variables in Experimental Design?

Full-disclosure, I'm not sure if this ENTIRELY on-topic. Often times, most texts will suggest that we code our variables. i.e. If we move from 345 to 350 to 355, we code our variables as -1, 0, and ...
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regarding generating synthetic data simulating the real data

We are trying to develop some predictive models. The current scenario is that we have to rely on synthetic data at first since the real data set will not be available quite soon. It is understandable ...
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30 views

Questions about mixed model design with repeated measures/nesting/incomplete design

I have data from a incomplete factorial experiment with repeated measures and potential nesting and am trying to figure out 1) the right way to design the mixed model to analyze the data, and 2) how ...
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10 views

Which analysis do I use for this experimental design?

Seeking feedback from those with a better quantitative mind than my own! Currently preparing my doctoral research proposal. I want to determine the impact that various levels of technology ...
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16 views

Regression Discontinuity Design Using Time of the Policy Change as the Assignment Variable

I am trying to study the impact of a policy change on user behaviour. In my context, a new policy is implemented on a specific week. Hence, everyone is exposed to the new policy at the same time. I ...
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1answer
37 views

Experimental Design with Factorial Block Structure

I'm designing a language-learning study with maybe 30 participants. My collaborators want each person to experience both of the methods we're using, so we are planning a crossover design. In addition ...
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Degrees of freedom in general full factorial design of experiments with missing observations

I am trying to calculate the total sum of squares SST and the degrees of freedom of an experiment with four features and three levels for each feature. It results in 3x3x3x3 samples (of course). ...
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37 views

Basic question about central limit theorem and sampling distributions

The CLT states that "if you have a population with mean μ and standard deviation σ and take sufficiently large random samples from the population, then the distribution of the sample means will be ...
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1answer
45 views

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 ...
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9 views

Incomplete randomized designs with uneven block sizes

Say we aim to estimate the effect of a treatment on the population and that we have, e.g. the following 12 experimental units: ...
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30 views

How to analyze $2^k$ design with replicates in SPSS (or R)?

I want to tune the parameters of an optimization algorithm. Since there are $4$ parameters: A, B, ...
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Difference between confounding and aliasing in 2^k factorial design

In statistics, particularly in experimental design, what is the difference between confounding and aliasing in 2^k factorial designs? Also how is a principal block related to the two concepts? I've ...
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What analysis to use? IV: multiple interdependent levels, DV: continuous variable

My dependent variable is a continuous variable, ranging from 0 to infinity. However, my independent variable has multiple interdependent levels. To illustrate, A person has 6 attributes: A1, A2,... ...
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16 views

Power analysis for polynomial regression

There are two variables, $X$ and $Y$. I am interested in the shape of the relationship between $X$ and $Y$, specifically whether it is linear, curved, or some higher order polynomial function, because ...
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Factorial ANOVA Hypothesis

If say I have an experiment with two categorical factors, a and b, in response to the variable x, and I set it in such a way that I try all possible combinations of the two factors, this is factorial ...
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2answers
63 views

What statistical test is appropriate for paired data where the same subjects are tested at multiple times?

In the test in question, we have data [measurements of discomfort] for the same subjects with different virtual reality experiences. We took multiple measurements of discomfort over the course of the ...
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Statistical design of experiments revealed some surprises — what next?

I recently became the manager of a complex piece of laboratory equipment. It has many knobs and dials to turn, and the different knobs and dials affect the significantly affect the responses I try to ...
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Experimental design: Same randomly selected stimuli versus different randomly selected stimuli in every subject

In an experiment, we’re going to present randomly generated stimuli to multiple subjects one trial at a time and measure neural responses to them. The stimuli are randomly generated to satisfy the ...
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Which tests should I use for my experiment

For each participant in my trial I have 35 parameters ($P_1,\ldots,P_{35}$), each measured at 4 different time points. Furthermore, the participants are partitioned into two groups $A$ and $B$, each ...
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15 views

How to model a multiple continuous factor, single response between 0 and 1 experiment

I have a fractional factorial design experiment that varies 12 continuous factors high and low that result in a single response which is 0 <= y <= 1. The distribution of the response appears ...
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14 views

Two groups: first with one measure, second with two measures: how to test between group difference?

In my research I have two groups: 1) Healthy group 2) Patients with disease I have a variable (quantitative) that measures some skin property for each patient. But diseased patients have two types of ...
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37 views

Create balanced incomplete block design with groups in R

I found the below R function on surveyanalysis.org. It creates balanced incomplete block designs (BIBD). I am trying to figure out how to alter the code to be able to partition the items per block ...