Questions tagged [experiment-design]
The study of how to structure an information-gathering exercise where variation is present.
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Structural equation modeling for experimental design data
I'm wondering if this is possible to fit structural equation model for experimental design data.
Problem
Suppose a researcher observed four responses $Y_1$, $Y_2$, $Y_3$, and $Y_4$ along with three ...
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Repeating an experiment - more valuable than sample size?
The setup is that I'm trying to understand how a computer program works, so I'm capturing some numbers every time a function is called. For example, I might be capturing the number of branches taken ...
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Multiplicative mixed models for analyzing variety-by-environment data
I got some nice data on multi-environment trials (MET) data for genotype evaluation and would like to use some new developed techniques as discussed in Smith et al. 2005. I'm specifically interested ...
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Mouse models - 'replicates' and analysis
I'm hoping to hear from someone who has worked on mouse models or similar biological analyses where there is a tendency to run 'replicates' of an experiment. I know multiple testing is a sizeable ...
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Testing significance of factors and covariates along with modeling causality among responses
I'm wondering how to test the significance of factor(s) and/or covariate(s) along with modeling the causal relationship among responses.
Let me explain this with a concrete example.
Example:
Suppose ...
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Review of case control matching algorithms?
Can you suggest a good review of case control matching algorithms? Algorithms that can be used to set up the matched pairs of one case and one control, or matched blocks of a case and multiple ...
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What is the meaning of an F value less than 1 in one-way ANOVA?
What does it mean if the F value in one-way ANOVA is less than 1?
Remember the F-ratio is
$$\frac{\sigma^2+\frac{r\times\sum_{i=1}^t \tau_i^2}{t-1}}{\sigma^2}$$
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Individuals standard deviations and/or standard errors for groups after implementing ANOVA?
I've seen couple of articles reporting individuals standard deviations and/or standard errors for groups even after implementing ANOVA. My understanding is that groups SE's should be based on ...
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How to perform diallel analysis in R?
Diallel Analysis using the Griffing and Hayman approach is so common in plant breeding and genetics. I'm wondering if someone can share R worked example on Diallel Analysis. Is there any good ...
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What is the proper ratio of mean squares for a two-level nested ANOVA?
I would like to analyse the following type of experiment using a two-level fully nested ANOVA. We have mice of two genotypes (Group factor) and for each of the genotypes we take a certain number of ...
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Comparing and understanding my linear regression result with a previous attempt
Update: I wanted to clarify that this is a simulation. Sorry if I confused everyone. I have also used meaningful names for my variables.
I am not a statistician so please correct me if I make a ...
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How to assess drug effects using annual death rate data?
I am planning a study to collect data of patients dying after brain infection versus number of cases for the next 5 years in 2 cities where they manage the disease with different drugs.
Will a year ...
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How to assess effect of intervention in one state versus another using annual death rate data?
I am a beginner in statistics. I have these unpublished data (cases and deaths) of a disease for 7 years (2004-2010) from 2 neighbouring states. The study was started in 2004. State 1 and State 2 ...
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What is a good way of estimating the dependence of an output variable on the input parameters?
I am evaluating a scenario's output parameter's dependence on three parameters: A, B and C. For this, I am conducting the following experiments:
Fix A+B, Vary C - Total four sets of (A+B) each having ...
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Book on designing clinical trials in oncology [duplicate]
I would like to have a good idea on how to design clinical trials in oncology. In that issue, I am looking for a compact book that could give me a good overview, with the emphasis on statistical ...
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Can someone help me understand what type of problem I am looking at? Not sure if this classifies as hypothesis-testing
Please pardon me if this question is not clear. I am not sure if I am using the right terminologies.
I have conducted an experiment in different environments multiple times. So my data looks ...
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How can I treat blocks in a split plot design?
In a field experiment involving crops, what is the difference in considering block as random or otherwise as fixed factor?
As far as I understood, random means that conclusion can be extended to other ...
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ANOVA on binomial data
I am analyzing an experimental data set. The data consists of a paired vector of treatment type and a binomial outcome:
...
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Should I re-shuffle my data?
We have a set biological samples that was pretty expensive to obtain. We put these samples through a series of tests to generate data that are used for building a predictive model. For this purpose we ...
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Experiment design for proportion
I would like to test a hypothesis that a database contains data that are correct in 95% or more of the samples.
I found this Hypothesis test for a proportion experiment design that looked appropriate....
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Can I test the effect of Block in a split plot design in R?
I have been confused with the problem for a very long time, and hope that somebody here can help me out.
I have a experiment installed in split-plot design, with 3 temporal groups as blocks, and 2 ...
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Taking advantage of many pre-treatment measurements
I am planing a pre-post treatment-control design study with a large number of pre-treatment measurements. I have subjects divided into a control group and a treatment group. For both groups, I will ...
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Appropriate test for multivariate experiment result with unknown distributions
I have an experiment with any possible (reasonable) number of parameters (independent variables). I run the experiment several times for each possible combination of my variables. The data I get will ...
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How to calculate sample size for simulation in order to assert some level of goodness in my results?
I am a stats newbie, so apologies in advance if I'm asking a braindead question. I have searched for answers to my question, but I find that many of the topics are either too specific, or quickly go ...
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How to predict and optimize a queue?
I am trying to determine if I can model my system as a M/M/1 queue and if so do the numbers I get from it help me at all.
I can model my system like this:
System Description
A. I want to spec out ...
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How to setup a laboratory experiment in Ecological Research under high natural variability
I am about to do a laboratory experiment in the scientific field of soil ecology and hydrology. Beforehand I want to make sure not to make any crucial mistakes, and therefore I would appreciate any ...
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Any ideas about how to analyze survival data with pseudo-replication (dependent data)?
I am a student, working with a team on a large-scale ecological experiment. We want to analyze survival data which has been derived from an experimental design with some pseudo-replication. This ...
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What to do with confounding variables?
I need to do an experiment. First let me describe present situation. The company that I work for is a cinema. It has a gaming section where people who are waiting for movies can pass time by playing ...
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At least, how many times an experiment should be replicated?
Is there a recommendation on the number of times that an experiment should be replicated? As many of you know, is not always possible to make many replicas. What would be the recommended minimum? Is ...
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How to do factorial analysis for a non-normal and heteroscedastic data?
I designed a field experiment with 4 independent factors but data is not normal and heteroscedastic. Friedman test (agricolae package) from R only fits for rbd. Can anybody suggest how to analyze my ...
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Unbalanced repeated measure design for the given data?
I have 3 factors
factor1 (treatment) with 2 levels (control, stress)
factor2 (Variates) with 12 Levels (Var1, Var2,....Var12)
factor3 (Time) with 12 levels (Week1, Week2,..., Week12)
The treatment ...
jacki
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Numbers 1-100, calculating how many I must pick to get x% of reliability
I would like to know the formula or method of calculating this.
For example, I want to know how many numbers I must pick in order to have 95% confidence that I will be within 2% of the average.
I'm ...
Greg
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How to model and test a decision support system (e.g. a terrorist warning system)?
I have reformulated the problem from a "dog barking warning system" to something else which hopefully, has less ambiguity. Instead, I will repose the problem as follows:
Let's assume that my ...
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Desirable and undesirable properties of Latin squares in experiments?
A cursory search reveals that Latin squares are fairly extensively used in the design of experiments. During my PhD, I have studied various theoretical properties of Latin squares (from a ...
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Setting up experiment for statistical analysis
I am looking at setting up an experiment concerning a hobby of mine, basically measuring a variety of parameters 'before' and 'after' and see which one, if any, gives the most reliable prediction of a ...
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Recommended books on experiment design?
What are the panel's recommendations for books on design of experiments?
Ideally, books should be still in print or available electronically, although that may not always be feasible. If you feel ...
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Correcting experiment results
We have performed a microarray screening of about 200 samples. In each sample we measure about 100 different variables. For technical reasons the screening of these 200 samples was divided into two ...
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References for how to plan a study
In an average (median?) conversation about statistics you will often find yourself discussing this or that method of analyzing this or that type of data. In my experience, careful study design with ...