Blog Archives

Random and fixed effects in sensory profiling

August 14, 2012
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Random and fixed effects in sensory profiling

I am reading Introduction into mixed modelling by N.W. Galway. It is partly a repeat of things I know, but I expect to use mixed models quite a lot the coming time, so it is good to repeat these things.My problem with this book is a sensory exampl...

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Trying Julia

August 1, 2012
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Trying Julia

In my previous post I tried building Williams designs in R. Since that code was running a bit slow, this was an ideal test for Julia. Big enough to be at least slightly realistic, small enough that it is doable.I am very impressed. Almost twenty fold s...

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Williams designs with 5 products

July 24, 2012
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Williams designs with 5 products

In a previous post I created small Williams designs for an even number of products. This worked very well, also because the number of permutations could be restricted significantly due to symmetry. Unfortunately this does not work so well with an odd n...

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Creating Williams designs with even number of products

July 12, 2012
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Creating Williams designs with even number of products

A Williams design is a special Latin square with the additional property of first order carry over (each product is followed equally often by each other product). In R the package crossdes can be used to create them. > williams(4)    &nbsp...

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Simulation in the profiling model

June 7, 2012
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Simulation in the profiling model

In this post I try to make a small simulation of the sensory (flavour) profiling data, and examine if the parameters of simulated data can be retrieved by the Bayesian model build in the previous posts.The conclusion is that it is difficult, the amount...

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A complete Bayesian model for sensory profiling data

May 22, 2012
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A complete Bayesian model for sensory profiling data

In this post I will try to add an important parts in the sensory profiling model I have been building. This concerns the question: 'Are all panelists equally reproducible?'. Obviously the answer is no, some are better than others. From this observation...

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Extending the sensory profiling data model

May 16, 2012
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Extending the sensory profiling data model

In this post I extend the multiplicative Bayesian sensory profiling model with effects for rounds and sessions. Is is not a difficult extension, but it brings the need for informative priors into the model. I do believe round and session effects exist,...

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Multiplicative effects in sensory panel data

May 7, 2012
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Multiplicative effects in sensory panel data

In a previous post I used JAGS to build the Bayesian equivalent of a two-way ANOVA. Effects were determined of products, panelists and their interaction. In this post this model will be rebuild to provide a more simplified and advanced model. The inter...

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Bayesian ANOVA for sensory panel profiling data

April 30, 2012
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Bayesian ANOVA for sensory panel profiling data

In this post it is examined if it is possible to use Bayesian methods and specifically JAGS to analyze sensory profiling data. The aim is not to obtain different results, but rather to confirm that the results are fairly similar. The data used is the c...

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Tuning GAMBoost

April 23, 2012
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Tuning GAMBoost

This post describes some of the simulation results which I obtained with the GAMBoost package. The aim of these simulations is to get a feel what I should tune and what I should not tune with GAMBoost. SetupIn the GAMBoost package one can tune qui...

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