Experimental design, or design of experiments (DOE), is the design of any information-gathering exercises where variation is present. In statistics, controlled experiments are usually implied, which involve an "experimental group" and a "control group". In the design of experiments, the ...

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When would you use an I-optimal design over a D-optimal design?

We were discussing in DOE designs that it was best for model development to us d-optimal designs to identify your design space. The common alternative would be an i-optimal design. When would it be ...
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57 views

How can I measure difference between non-parametric data with many zeros?

I'm comparing two groups of students by their course activity and I'm struggling a little to determine the best way to test for significant difference. The data is non-normal, and very prevalent with ...
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How do I calculate the sample size required for a crossover AB|BA study?

I would like to know whether it is feasible to conduct this study. We have a subset of people in facility A (n=1300 per year), of which a proportion of these present a condition (n=18). Similarly, we ...
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42 views

Misfitting of drift rate in Wiener model

In a binary-decision experiment, the accuracy and response time of some subjects were recorded. My goal is to fit a Wiener model to response time and accuracy data. The binary experiment has three ...
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18 views

Advantages of counterbalancing vs. randomizing stimuli

I'm designing an experiment, in which 40 participants answer 10 questions, 5 in condition $A$ and 5 in condition $B$, and I'm interested in the difference between the two conditions. It's not clear ...
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22 views

Clustering MVT response data by audience

We are doing multivariate testing 4 possible values for each of 3 variables on a landing page: (a) offer presented, (b) product claim message displayed and (c) image used. So, 12 dummy variables, 64 ...
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Response surface models using quantitative variables

This relates to the mineral industry so a little context first. We are trying to estimate the uncertainty in the amount of ore that can be recovered from an ore body mine. This depends on things ...
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6 views

Multiway anova doubts

I am new to statistical inference. I have read about one-way/multi-way anova and also between subjects and within subjects design. I would like to conduct a subjective quality test and analyze the ...
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40 views

what should be the null hypothesis?

conduct a test hypothesis to show that it takes longer for people with average fitness to successfully complete physical therapy as compared to those with above average physical fitness. Test at ...
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10 views

How can I prove the variance of residuals for an unbalanced one-way layout?

How can I prove the variance of residuals for an unbalanced one-way layout? var($e_{ij}$)=$σ^2$($1- \frac{1}{n_i})$ here i = 1,...., a j = 1,....$n_i$ where $e_{ij}$'s are the residuals. where ...
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What wrong with this experiment methodology?

The following experiment was devised: a group (random) was divided randomly into 2 : Half were give coffee A the others coffee B, all rated it on a 1-5 Likert scale. Results where analyzed using ...
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20 views

experimental longitudinal design?

Is a longitudinal study really by definition/always correlational? How about a repeated-measures experiment: I would've called that an experimental longitudinal design. (For example, you randomly ...
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13 views

Why do contrasts or contrast sum of squares have one degree of freedom?

I have repeatedly seen that contrasts or contrast sum of squares are mentioned to have one degree of freedom. I'm wondering why this is the case. Is there an obvious explanation? Shouldn't they have ...
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8 views

Acceptance Sampling Plan

I was reading Acceptance Sampling Plan but didn't understood when should I use single sampling plan , when double sampling plan , when multiple sampling plan and when sequential sampling plan. Also ...
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29 views

How to interpret D-Efficiency in Experimental Design?

I created an orthogonal design in R using AlgDesign package. I got 14 profiles and some output: D =0.2519353; A = 5.462121; Ge = 0.748; Dea = 0.714. How to interpret D , A , Ge and Dea? Also, In ...
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7 views

ANOVA table for alpha latice design?

I have my trail in alpha lattice design with three replications, 32 blocks in each replication, 10 plots per block, and with 320 treatment, please suggest to me an ANOVA model for this analysis.
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34 views

Difference between “Design based approach” and “Model based approach”?

In a pdf file, i found the following thing which i have not understood at all. ‐ one view (e.g., Heckman, 2008): causality is model‐based: causality only exists within the framework of a theory ...
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24 views

Study design: equal/unequal sample sizes

I have recently sent a paper on aflatoxin levels in nuts for publishing. The aim of the study was to analyze a total amount of 106 nuts. The nuts were divided into four categories: walnuts (n=33), ...
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27 views

Adaptive Sampling Design

In a pdf, the definition of adaptive sampling design is written as : "An adaptive sampling design is one in which the selection of units to include in the sample depends on ...
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61 views

Do the different levels of treatment in a completely randomized design come from different population?

Suppose in a completely randomized design , a treatment A have four levels. When we check whether the means of four levels are statistically significant ,i.e., $$H_0:\mu_1=\mu_2=\mu_3=\mu_4$$ ...
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AI battle (or experiment with 2 or 3 element sample space) - what number of experiments to do to get win rate with choosed statistical significance?

I make script that runs Wesnoth game in 1vs1 AI mode several times. Both sides play on mostly symmetrical starting condition. Each game ends with player1 win or ...
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11 views

multiple repeated within subjects pre test measurements in fully crossed design

Which statistical test should I use if my design has a baseline pre test for 3 treatments? Each subject gets all 3 treatments each on different days. Each day has a pre treatment baseline measure. ...
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16 views

Randomization for multi-site clinical trial, screen failures

Two questions about appropriate randomization procedures for a small two-armed trial at 3 sites. About 100 participants total, evenly split between study arms. First, we are concurrently enrolling ...
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Should I use baseline condition when comparing two “treatment” conditions?

I'm interested in comparing performance (measured in proportion of correct trials) on a visual perception task between two "difficult" conditions. Normally, I'm interested in measuring performance ...
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91 views

Is it valid to use a generalized model with no replicates

I've got a designed experiment that is a long-term agricultural station. The field is divided into 11 rows and 6 columns (each column has two sub-columns). Each resulting plot represents a unique ...
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DOE Power Calculation for Interaction Terms

I was using Monte Carlo to determine the a-priori power for the terms in a designed experiment. To do this I used the following procedure: Set an effect size I expect to see in my response Use the ...
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Clustering standard errors for respondents who move during treatment period

I am conducting an impact evaluation, but the question applies generally to any situation where observations move between cluster-units during the course of treatment. I am using robust standard ...
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How to design my experiment

First question: I am interested in determining the best settings for a live video feed that must have very good quality. I have identified 4 factors that affect the video feed, and there are 2 levels ...
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38 views

Is Randomized Complete Block Design a two-way anova?

Isn't Randomized Complete Block Design a two-way anova ? Can it be one-way ? As far i understand, since there is treatment effect and also block effect in RCBD, it is two-way anova. But can it be ...
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30 views

minitab p-values of interactions

I am having some trouble in Minitab. I constructed a L16 Taguchi orthogonal array for 5 factors which all have 2 levels by using Minitab, and I need to check if all the interactions are significant or ...
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42 views

What analysis can I do when I have different design and I would like to analyse together?

I study the relationships between plant community (forest restoration) and soil properties. My experiment is 15 years old, and I have a block design with five treatments and three replicates. I have ...
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18 views

How would I analyze the change in bacterial populations in different nutrient solutions?

I am planning an experiment and have trouble finding out the best method of analyzing the data, I would like to do power analysis beforehand. I have 6 bottles, 3 with nutrient solution A, and 3 with ...
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2answers
52 views

When to create a control group with paired T test

So if I wanted to measure the effect of a drug on a group of people, I think I would use a paired T test based on my research. But what if something caused a change in my group that I did not account ...
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2answers
32 views

sample versus population in experimental data

I am not statistically oriented, so I am hoping you might be able to help. I have a small lab setup that mimics a larger natural process (natural disaster). I have designed and completed 46 ...
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PERMANOVA Design

My aim is to quantify temporal change in community composition by measuring community composition through time at several plots using randomly placed quadrats. The idea would be to repeat surveys at ...
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A potential confound in an experiment design

Overview of the question Warning: This question requires a lot of set-up. Please bear with me. A colleague of mine and I are working on an experiment design. The design must work around a large ...
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33 views

Number of experiments when expected value = probability [closed]

How many times I should conduct experiment to have expected value which will be within some interval (for example 2 SE) of probability. For example how many times I should toss coin so that frequency ...
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7 views

Design of experiment runs

If now I having a full factorial DOE on a 4 factors 3 levels, 10 replications for each, is it my total runs will be 810 ?
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Does a within groups design necessarily mean the data is matched?

I am seeing conflicting information on this. The design is within groups with 4 groups. Each user experiences all four groups in a random order. There is no real reason the results of one group would ...
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174 views

Binary outcome in randomized controlled trials — OLS or logistic?

I'm running a randomized controlled trial which has good balance in the co-variates. I'm unsure whether to use: OLS: $P(Y_i=1) = \beta_0 + \beta_1 \text{Treat} + \epsilon_i$. This is problematic ...
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22 views

Confustion about exam question

I'm preparing for an exam and I came across this question in a book. Below, I understand that we have to assumed a split plot in time analysis with 3 way factorial with 3 drug * 2 sex * 4 time levels. ...
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Control group in Incomplete Factorial Design

here, in title of Incomplete Factorial Design, it is written that " it is actually impossible to implement a group that simultaneously has several levels of treatment factors and receives no ...
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$3^3$ factorial design

Suppose in a $3^3$ factorial design, factor A has three levels. We want to test the significance of A and after setting hypothesis $$H_0:\alpha_i=0 \quad\text{for}\quad i=1,2,3 \quad\text{Vs.}\quad ...
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How to find the levels (+ or -) using the words in a Fractional Factorial?

I'm stuck on this question and would appreciate any help! Q: Given the partial defining relation I = -ABD = -ACE = BCF for a $2^{6-3}$ fractional factorial design, obtain the complete defining ...
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192 views

Choosing Location Based Control Group

I have a dataset that tracks activities at particular locations. The dataset is essentially, timestamp, latitude and longitude, indicating an activity at that lat-long and that time. I plan on ...
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20 views

Estimating better performing variation with unkown sample size

Scenario: We are in the app business and trying to optimize for downloads in the app store. Things like the shown screenshots, the text, the icon etc. can be changed and will have an influence on the ...
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15 views

How to select subjects in my experiment?

I had two visualization methods (Vis A and Vis B). In order to answer following questions: 1) Which one of these visualization perform better? 2) How different genders (male, female) perform with ...
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1answer
29 views

Study Length Over-Estimating Hazard Ratio?

Are cox model studies over too long a time-scale at risk of over estimating (or under estimating) a covariate's effect on hazard? I'm studying inbreeding in a captive animal population. Some ...
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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 ...
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Intuition for what happens to the standard deviation after plugging a normal variable into a function

Let's say I have a normal variable $X$. I feed $X$ into some function, which applies varies mathematical operations to it - for instance, addition, subtraction, multiplication, division, $x^r$, $e^x$, ...