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Questions tagged [experiment-design]

The study of how to structure an information-gathering exercise where variation is present.

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Why can't interaction be measured with a complete block design? [duplicate]

I am struggling to understand why interaction cannot be measured in a CBD. While many sources say it is because there is only one observation per block/treatment combination, could you not compare the ...
Laura Edwards's user avatar
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Looking for an intuitive explanation of D-Criterion for Optimal Design Problem

I know only a little about Fisher information and optimal experimental design, but I'm trying to better understand the subject. If I have an experiment composed of a single detector and my detector ...
David G.'s user avatar
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Show conditional independence in randomized experiment

I'm new to causal inference, and I have a question regarding a potential causal relationship. I'm wondering if the following assumption holds: $(Y_i(1), Y_i(0), X_i) ⊥ Z_i -> (Y_i(1), Y_i(0)) ⊥ Z_i ...
user408381's user avatar
2 votes
1 answer
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Regression using unordered combinations, sign of predictor depends on order

First time poster here. Is there anything wrong with the following regression approach? EDIT: After following the advice of the accepted answer to include the multiple-membership effect, I wanted to ...
Evan Stegner's user avatar
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25 views

What is the correct way to analyze this data in a mixed model approach?

I have an experiment with rates of an waste in complete randomized blocks designs, with evaluation of soil fertility and tree heights/diameters over the years. Which is the best model to fit this data?...
ntrentin's user avatar
7 votes
2 answers
591 views

average revenue per user increases each country but decreases when combined

I'm trying to figure out what could be some reasons when we do the AB testing we're seeing average revenue per user increases for each country but when we calculate the overall average revenue per ...
ggggogloria's user avatar
6 votes
1 answer
117 views

How is it reasonable that randomised controlled trials can be used to perform causal inference?

I understand that randomised controlled trials (RCTs) are used to perform causal inference, but I'm a confused about how this is reasonable. Let's say that we have a treatment, and we want to find out ...
The Pointer's user avatar
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Factors in a multi-factor design

I have trouble distinguishing between a factor and a replicate. For instance, in my class notes, there is a question: To study the variability in CO2 emission rate by global regions 4 countries: US, ...
Matata's user avatar
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How to handle multicollinearity with varying length and type of conjoint treatments?

We ran a complicated experiment and are struggling to build a linear model that estimates everything we're interested in. We showed each person a description of a product (for illustration, let's say ...
Tia's user avatar
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4 votes
1 answer
102 views

Experiments where the treatment is such that the act of applying the treatment to some people within the group and not others undermines the treatment

Let’s say we have an experiment where we want to apply some treatment to some group to test whether the treatment “works”. But the treatment is such that the act of applying the treatment to some ...
The Pointer's user avatar
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How do I calculate effect size in a pretest-posttest three group randomized study for two planned contrasts (ANCOVA)?

I am having a hard time calculating the individual effect sizes for ANCOVA simple contrasts ($1$ vs. $2$ and $1$ vs. $3$) in a randomized pretest-posttest design study with three groups. In the ANCOVA,...
Eniko's user avatar
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Can regression to the mean also impact heterogeneity?

I understand Regression to the Mean (RM) as a naturally (and likely randomly) occurring shift in the scores of a sample of extreme subjects (super high or low scorers) from each measurement time to ...
Simon Harmel's user avatar
4 votes
1 answer
149 views

how to deal with treatment dropouts in experimental designs

I conducted a between-subjects experiment with one 3-level factor (high group vs low group vs control group). Because of dropouts from the treatments, the final distribution is control group: 85 ...
dondu's user avatar
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5 votes
1 answer
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Performing a Difference-in-Difference Analysis where the Control Group is Already Treated

I'm involved in a project where the outcome is the proportion of cancer patients who have received surgery. The treatment event is a state-level policy change that mandated moving all these cancer ...
user8408275's user avatar
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How to Include a 'No Shift' Scenario in a Temperature Shift DOE

I'm currently working on a Design of Experiments (DOE) for a process that involves temperature shifts at three different times. My challenge is incorporating a 'No Shift' scenario as one of the ...
Megazord's user avatar
3 votes
1 answer
79 views

How do data/observations themselves contribute to our ability to make determinations of whether a hypothesis is true or false?

Let's say that I have a hypothesis, and I'm trying to determine whether the hypothesis is true or false. If I remember correctly, in statistics, the standard philosophical view is that, technically, ...
The Pointer's user avatar
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Is it possible to use simulated (bootstrap) A/A tests of historic data to estimate the impact of confounding factors on the treatment effect?

I recently heard a proposal for a method to measure the degree to which confounding variables impact historic results of A/B tests. In order to ascertain the degree to which confounding has impacted ...
McGez's user avatar
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How to code a lme, lmer, or glmer model for a split-plot design (ANOVA)?

I have a study where the initial height of seedlings were measured at year 0 and again 11 years after treatments were applied and a net change in height was recorded. I have a split-plot design as ...
kryogenic7's user avatar
2 votes
1 answer
100 views

Power analysis for a quasi-experimental factorial design 3(manipulated) x 1 (measured) ANCOVA

I'm experiencing an hard time looking for the proper analysis to use to compute the power for an experiment i'd like to implement, so here is my question for you. I'd like to run a quasi-experimental ...
GT87's user avatar
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What is the appropriate design for a discrete choice experiment?

I need to develop a discrete choice experiment in R, which is an unlabeled experiment. However, after delving into the theory behind discrete choice experiments, it remains unclear whether there is a ...
Amy95's user avatar
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1 vote
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Discretization in regression, experimentation, and causal inference as deafult [duplicate]

It crossed my mind that when designing an experiment and you're not interested in NHST but full regression model where coefficients for treatment exposure and relevant covariates are desired, perhaps ...
jbuddy_13's user avatar
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18 votes
3 answers
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Causal diagrams necessary in randomized controlled trials?

I understand how a properly administered RCT rules out confounders because there are no variables influencing the treatment/control group assignment except randomization (meaning no backdoor paths ...
RobertF's user avatar
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How to mathematically prove the "transitive property of nested predictors"?

QUESTION I am studying the structure of experiment data sets, and I want to propose a rule that I call the "transitive property of nested predictors". The general idea is that… if there are ...
Chris Science's user avatar
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Validating my experiment design and Mann-Whitney U test usage

There are four different methods I use to generate solutions for different domains. To determine which solution is the most useful, I want to conduct an experiment with participants. As I have some ...
Max Bragilovski's user avatar
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35 views

Caclulating the standard error of difference in Conditional Average Treatment Effects (CATEs)

Some perceive scientific information (for example, scientific evidence of climate change) as accurate, but others don't. I want to know under which condition this biased evaluation increases or ...
Jin's user avatar
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Which field of mathematics should be used to formalize the analysis of a dataset's "geometric" structure [closed]

I want to know if mathematical formalism can be applied to understand the "geometric" structure of an experiment's data set, and esp. to the relationships between its categorical predictors. ...
Chris Science's user avatar
2 votes
0 answers
30 views

Using Difference-in-Differences With No Natural Groupings

I'm running across a number of analyses at my organization where people are doing difference-in-differences on individual-level data with no natural groupings. For example, one looked at the effect ...
kypc's user avatar
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8 votes
1 answer
153 views

Is there a good reason for a lab to repeat experiments instead of conducting a single larger blocked experiment

It is not uncommon for biologists to repeat experiments to confirm initial results. Intuitively this makes some sense but to me seems inefficient and potentially problematic. (For example, one client ...
George Savva's user avatar
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39 views

Appropriate design for two experimental conditions and incomplete blocking

I'm planning to perform an experiment in which I will be assessing the role of two experimental variables (A: 6 levels, B: 4 levels) on a defined outcome which, however, might be affected by external ...
Mabri's user avatar
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Conceptual question on Recognition vs conformation

So, this is a conceptual question on the design of a model. I am getting started with ML and on a slight time crunch to get some results. My problem is not a classical recognition problem. It’s more ...
H Khalid's user avatar
5 votes
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Use of other ICU patients as control group

I am reviewing an article that is not yet published, so I cannot be too specific. Briefly, the authors did an unmatched case-control study. The cases were patients admitted to the ICU for a specific ...
Peter Flom's user avatar
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0 answers
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Testing correlations between different varibles from two measurements

The field study investigates the relationship between root traits and plant performance traits in 12 genotypes, using a randomized complete block design with four replications per location. Root ...
Ales Kolma's user avatar
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0 answers
27 views

How to choose the sample size

How do I choose a sample size for a multiple factors irrigation experimental research? Here is what I mean, I want to compare the effect of precision irrigation and conventional irrigation on crop ...
Salami Chakour's user avatar
1 vote
0 answers
26 views

Mixed effects model in R with subsampling in replicates

I am working on a mixed effects model in r where I have 2 treatments, 5 replications and subsampling with each site. I dont have access to the raw subsampling data though, I just have the mean effect ...
Caleb Niemeyer's user avatar
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0 answers
14 views

How to adjust blocks in a 2x2 factorial experiment (Minitab)?

I'm currently in the planning phase of an experiment involving 2 factors, each with 2 levels, and 3 replications per combination, resulting in 12 experimental runs. In Minitab, the suggested blocks in ...
Sina Ardalan's user avatar
7 votes
2 answers
132 views

Designing an experiment to assess the form of a distance measure

BACKGROUND: I do research in budget-proposal aggregation: each person reports their ideal budget-allocation, and a central authority has to decide on an actual budget-allocation. An important ...
Erel Segal-Halevi's user avatar
4 votes
1 answer
48 views

AB Testing with and without counterfactuals

My boss wants us to run a simple experiment where we manipulate the search results on our website. He is insisting that we must have counterfactuals for the results to be valid. The way I see ...
Daniel's user avatar
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2 votes
0 answers
45 views

Validating power analysis

I'm currently running some experiments in web. The main idea is to validate the impact in some conversion metrics. The typical funnel we have is: Traffic -> Signup -> some Activation event. Our ...
marz's user avatar
  • 187
4 votes
1 answer
74 views

How does G*Power calculate sensitivity in z-test for two independent proportions

I am trying to recreate sensitivity calculation in Python by applying the same methodology as used in G*Power z-tests > Proportions: Difference Between Two Independent Proportions > Sensitivity: ...
Eugene Krall's user avatar
0 votes
0 answers
11 views

What is the relationship between maximum entropy sampling and bayesian d-optimal design?

In regards to optimal design, specifically sequential design or active learning for parameter inference (e.g. linear regression). As I understand it, Bayesian D-optimal design maximises the expected ...
Septimus Boshoff's user avatar
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0 answers
22 views

Degree of Freedom in DoE modeling

Past the standard full factorial and fractional designs, I am getting the impression that non-regular designs (OME, Hall, mixed-level OA, etc.) are just trying to fit in as many factors as possible. ...
Kaiwen Wang's user avatar
1 vote
0 answers
16 views

How to fractionate a 2^4 x 3 factorial with a nominal categorical

I've only just been taking a dive into DoE, so I'm still green on how to setup the designs according my experiment, so this question is more about confirming my understanding of experimental design. I'...
GreenEars's user avatar
1 vote
0 answers
31 views

balanced and unbalanced dose response experiments

Consider a dose response study where there are four active treatments (from the highest dose and lowest dose) and also a control. One goal is to test the hypothesis that treatments are more effective ...
user13154's user avatar
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5 votes
1 answer
154 views

How should I analyse this experiment with two blocking factors

In this experiment, a machine is used to compare the wear resistance of 4 different types of rubber-coated fabric (variable mat coded A, B, C and D). To do this, ...
Vivek Sharma's user avatar
3 votes
1 answer
292 views

What is a Randomized Complete Block Design. How do we create one and analyze it?

I have been reading about experimental design, and Randomized Complete Block designs (RCBD) in particular and I have a few queries. What exactly is a randomized complete block design ? Is there a ...
Vivek Sharma's user avatar
2 votes
1 answer
72 views

How to consider independent samples in a mixed-design experiment?

I collected data from an experiment with a mixed-design, specifically a 2x3x4 mixed-design, where the factors are populations (2 levels), conditions for the first population (3 levels), and conditions ...
Andrea Gulli's user avatar
2 votes
2 answers
182 views

Statistically testing for differential attrition in R?

Context I have a randomized controlled trial with three groups and three time measurements (pre, post, follow-up). I noticed that from pre to post, and then from post to follow-up, the attrition rates ...
rempsyc's user avatar
  • 281
2 votes
1 answer
29 views

Physical model for multilocation RCBD with repeated measures in time

I am trying to write a model for an experimental design that looks like this: There are 5 farms (A,B,C,D,E) , and each farm has a RCBD design with 2 treatments(1,2) randomized in 4 blocks in each farm....
Rabin KC's user avatar
1 vote
0 answers
36 views

Is it better to sample more time points or more replicates at constant sample size?

I would like to analyze my data with a linear regression: t*k = x x is my measurement with some error t is time I want to fit k as best as I can with the best ...
user1816847's user avatar
-1 votes
2 answers
78 views

What are the current major issues and controversies in clinical trials design and analysis? [closed]

As per the title, I would like to know what are currently the major issues and controversies in clinical trials design and analysis.
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