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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What are the statistical implications of assigning treatment and control in time series study under 2 different approaches?

I have a project wherein my group wants to measure the effect of counseling at-risk students on their academic outcomes. There are 1,000 students who will be enrolled during the current academic ...
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18 views

Experimental design and mixed models

I want to test effect of 3 PH on larval development. I would like to know what is the best experimental design and statistical analysis. We can only use 3 compartments of sea water, each one with a ...
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Sample size calculation for multilevel, longitudinal experiment

I'd be grateful for any advice about how to do a sample size calculation for the following design. We are interested in the impact of two variations of an intervention on hospital in-patients' ...
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26 views

Controled Factorial Experiment Design: which name or resource?

I'm designing an experiment which has to factors (A,B) with respectively 4 and 5 levels. Since this is quite a large amount, I figured I use a factorial design. However, it is unclear whether the ...
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20 views

Is it OK to take “Analysis of Variance in Experimental Design Models” Before a Regression Course?

I am a math major starting a MS program in statistics. I have taken an undergraduate sequence in stats (basics of distributions, estimation, hypothesis testing) but never a formal course in ...
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31 views

How do I define generators in Minitab

How do I define generators in Minitab 16? I have an experiment design (DOE) with 5 factors and 2 generators. I entered D=ABC E=AC in the box of generators but it says only F through G ?
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33 views

Can I hypothesise an insignificant mediation? (Very basic stats)

This is for a simple psychology report. I was wondering if I could hypothesise an insignificant mediation. Eg: "...based on this research it is predicted that group identity is not a significant ...
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37 views

Establishing significance levels post-hoc

Proper frequentist procedure says that we should establish a sampling plan, statistical analysis and significance level before we start an experiment. We then report whether or not we reject H0 for ...
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10 views

Interpreting covariates in 2 by 2 MANCOVA

I am doing 2 by 2 MANCOVA with experimental data set. Followings are variables I used. DV1, DV2, IV1, IV2, and C1 where DV=dependent variable, IV=independent variable, and C=covariate. Consistent ...
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1answer
102 views

What type of Research Design?

In an experiment, 25 subjects (Group A) are assigned to play an adventure game (with audio and non-audio) while another 25 subjects (Group B) are assigned to play a strategy game (with audio and ...
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2answers
36 views

Difference between Research Design and Experimental Design

What is the difference between Research Design and Experimental Design? I can't see any difference. Both of them need to establish Causality. Both of them are the arrangement for collection and ...
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Type-1 Error of the Two-Stage Design

Background on Two-Stage Designs In clinical trials, we are often interested in the response rate $p$ for an experimental treatment. In a typical trial, we might expose $n$ patients to the treatment ...
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1answer
21 views

How to deal with outlier in the experiment

My question is related to this one. I'm working on an experiment involving transferring data between different locations all over the world via the Internet. As the Internet can be busy, sometimes it ...
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24 views

What's the sample size required to confirm that two treatments are identical?

Goal: Determine if a machine is defective Say I am going to give the same treatment to a group of people. I have a machine that will randomly split them into $2$ groups before giving the same ...
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Augmented split plot experimental design

I planned a field experiment with different genotypes according to an augmented design (check repeated entries plus unrepeated entries). Since I am testing a segregating population, each plot split ...
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1answer
58 views

What is the meaning of $A(B^2)$ interaction in a 3 level factorial with 2 factors $A$ and $B$, when the factors are qualitative?

I understand that when the factor is quantitative the $AB$ interaction can have a linear component and a quadratic component and so $AB^2$ makes sense there. But when we have qualitative elements how ...
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46 views

In an experiment w/binomial responses, some subjects gave the same answer for all trials. [How] can a Mixed Effects model (R's lmer) deal with this?

I recently ran a pilot of an experiment on Amazon's Mechanical Turk. In the experiment, participants read 5 items, and answered a yes/no question about each one. A between-participants factor was ...
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1answer
150 views

How big is “sufficient” sample size?

I am currently doing some tests with some specific parameter settings to characterize a process. I roughly remember that a widely used rule of thumb for lab tests and whatnot is a sample size of 5 or ...
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1answer
47 views

larger sample size or more accurate measurement?

This question is completely theoretical in the sense that I don't have any real data. Suppose I am designing a study, in which I will go measure N pairs of (X,Y), then the goal is to build a ...
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17 views

Split plot ANOVA or t-test

I did a study in which I wanted to see if a teaching intervention would have an effect on student learning. I nonrandomly divided students into two groups, a control and experimental group, and gave ...
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2answers
92 views

Designing Computer Science experiments (Hypotheses and errors?)

For my master thesis I want to set-up several experiments. One thing my professor has been complaining about is that most computer science experiments are lacking scientifically. To not fall into this ...
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Response-surface methodology vs. 3-level full-factorial [closed]

What is the difference between a Box-Behnken design, a central composite design and 3-level full-factorial design? What are the advantages or disadvantages of one design over the others?
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23 views

How to run regression on a Taguchi design?

I'm trying to run a regression analysis on a Taguchi design. I have five categorical control factors, one of them with two levels and the other four with three levels. I want to generate a regression ...
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20 views

What statistical tests to run given the design?

I have 3 research questions. 1) Does increased hyperlink insularity cause better user understanding? 2) Does increased hyperlink insularity cause better user perceived security? 3) Does increased ...
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1answer
35 views

analysis of alpha lattice design

Are there R some packages for analysis of alpha-lattice (0,1) designed experiment? My experiment includes two factors with two levels. The tests are performed in two replications with twenty blocks. ...
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1answer
88 views

Split plot with factorial design vs three way ANOVA

I have three site temperature types: cold, medium, and hot. This is a fixed effect - I am specifically am testing if temperature affects my response variable. I believe temperature type is my 'block'. ...
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21 views

categorical variables in factorial design

One dependent variable, One independent continuous variable and One independent categorical variable (two levels only). Factorial design is easy except I don't know how to add center points. I am ...
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58 views

Which Statistical Technique (ANCOVA or Taguchi methods) for this problem?

I have one qualitative factor (Treatments) and two uncontrollable factors, temperature and moisture, with one response variable. I'm confused whether I should use ANCOVA with temperature and moisture ...
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Alias Structure of one-fourth replicate of a $4^2$-Factorial Design with interaction $\text{A}{B}^3$ confounded

For finding the Alias of main effect A , i started as the following : $\text{A}$$\times$ $\text{A}{B}^3$$=\text{A}^2\text{B}^3={(\text{A}^2\text{B}^3})^2=\text{A}^4\text{B}^6=\text{B}^2$(mod ...
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1answer
32 views

Redundancy in Performance Measures

I have a performance rating that correlates positively with a variety of other parameters used individually to evaluate the performance rating of a given operation. However, I suspect that many of ...
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19 views

How do I choose which design of experiments method to use?

I'm setting up a computer simulation (which I know changes the design of experiments methods) and I can't really determine how to choose which design of experiments (DOE) method to use. I'm a little ...
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37 views

Error for combining multiple binomial distributions

This problem is somewhat involved and I have a partial solution so bear with me. I will illustrate the problem with an example. Lets say we have two processes and we want to know which has a higher ...
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3answers
111 views

How should I analyze my data?

I am new here, so I hope this question is on topic. I understand a little about statistics, but my knowledge of what methods to use in real case scenarios is a little limited. I want to statistically ...
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2answers
36 views

alternative formulas for standard error of a difference between two means?

I have a question that seems basic but I found two alternative answers online so I thought that I should ask for advice. I have an experiment where each subject makes decisions about target words in ...
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2answers
48 views

Interactions between covariates

Suppose I have a sample with two covariates whose levels are associated with some response; e.g., the mean height of a plant at 6 months is modeled by two factors: cultivar of plant (say, $A$ versus ...
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94 views

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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1answer
25 views

How is LSD an incomplete three-way layout?

How is the Latin square design(LSD) an incomplete three-way layout? In this context, let me ask also what is a complete layout?
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Is a Chi-squared test sufficient to tell me if my process change was “good enough”?

Experiment Design: Process: Outputs the order in which to do the work (assumption: ordering of work items is most preferred/valuable by stakeholders) Work items: The process above produces a rank ...
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why is orthogonality represented geometrically in DOE and is fractional factorial designs are orthogonal?

I've noticed in many places that it is common do describe experiments in DOE and orthogonality as a geometric figure, why is that? Also is it connected to orthogonality?
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1answer
60 views

How to interpet residual plot?

As a part of a design of experiments course I'm taking, I ran an experiment at home. The experiment was checking how water boiling time changes under certain factors (5 overall factors) all which had ...
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2answers
71 views

Bayes theorem an experiment design

Let's say I design an experiment to test the hypothesis, "Agent Z causes cancer". Of $N$ people in the experiment group, $x$ get cancer. Of $N$ people in the control group, $y$ get cancer. The ...
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1answer
81 views

Observational study with many data Vs. Experimental study with fewer data: Which has more value?

So I have recently been debating two possibilities for determining the effectiveness of, let us say for simplicity, a single marking strategy for getting return customers. Let us assume that we have ...
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56 views

using t-test to compare multiple slopes?

I work with an escape response. Basically, I want to find differences between animals that should run and animals that stay still when a stimulus is applied to them. I've been trying several ...
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2answers
23 views

What statistical tests would be effective for this design?

Here the basics: Group 1 is the control group, they are given a specific website to use. Group 2 is the experimental group, they are given a similar website, with adjusted hypertext properties. ...
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1answer
35 views

Fractional factorial design. only main effects considered

I have 15 factors which I want to optimize. Instead of running a fractional factorial design consisting of 32 runs, if I run a design consisting of 16 runs, will I only get main effects or any second ...
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14 views

Whole Plot Optimizations for Designed Experiments

I was looking into the DoE.wrapper collection of packages for R and I was interested in generating a split-plot design like I might in JMP. In JMP I can specify ...
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30 views

Categorical vs Continuous Variables in AlgDesign and DoE.Wrapper

I have been used to using JMP to generate custom designs for a little bit and wanted to explore generating designs with R using the DoE.wrapper packages. I wanted to generate a design that had one ...
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21 views

Experiment design

We have x1 and x2 representing variations in temperature and pressure and the response is yield of penicillin. What is the practical reason for using the points (-1,-1), (-1,1), (1,-1), (1,1) rather ...
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Research design regarding similar names and comovements

I have a small question about a small research that I wanted to do regarding stock symbol similarities and their abnormal returns. I have about a sample of 10 000 stocks and I calculate how much they ...
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1answer
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Course of Action for 2x2 tables with 0's in cell and low cell counts

I'm comparing two groups A, B after cross tabulating them with cases and controls. I get a table as such: Control Cases A 8 0 B 14 0 ...