Blog Archives

JAGS model Fe concentration in rainwater including values below detection level

December 1, 2013
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JAGS model Fe concentration in rainwater including values below detection level

In my previous post I ignored the fact that some data are below the detection level. I would not know how to handle those in a mixed model from lme4 or nlme. However, JAGS can handle these values. Next to that I kept the usual independent variables, su...

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Dutch Rainwater Composition 1992-2011

November 24, 2013
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Dutch Rainwater Composition 1992-2011

Last week I examined rainwater composition 1992 to 2005. There is additional data, but National Institute for Public Health has changed equipment in 2005. This week I will add those data.DataData is in a number of spreadsheets. The scrip...

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Dutch Rainwater Composition 1992-2005.

November 17, 2013
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Dutch Rainwater Composition 1992-2005.

After reading Blog About Stats' Open Data Index Blog Post I decided to browse a bit in the Open Data Index. Choosing Netherlands and following Emission of Pollutants I ended on a page from National Institute for Public Health. The page&n...

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A small comparison of bio-equivalence calculations.

November 10, 2013
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Last week I looked at two-way cross-over studies and followed the example of Schütz (http://bebac.at/) in the analysis. Since the EU has its on opinions (Questions & Answers: Positions on specific questions addressed to the pharmacokinetics working party) and two example data sets, I was wondering how the various computations compared.Data There...

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Statistical aspects of two-way cross-over studies

November 3, 2013
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I ran into this presentation on Statistical aspects of two-way cross-over studies by Ing. Helmut Schütz (http://bebac.at). He presented some code and referred to the bear package. The bear package is menu driven, which is not my thing. I had to try and do that in R via other packages. The aim is to estimate if the...

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Symmetry in Williams designs

October 27, 2013
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Based on some comments I am looking at using symmetry to obtain Williams style designs. Symmetry allows reduction of the number of combinations examined hence faster calculation times. Two avenues are examined. Both work for a low number of treatments....

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Carry-over balanced designs for 8 treatments

October 19, 2013
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Those are Williams designs you might say, but it has become clear to me that Williams designs are just a subset of all carry-over balanced designs. Not through hard work of mine, comments by Apn on my previous post Creating Williams designs with e...

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Prices of houses in the Netherlands

October 13, 2013
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Prices of houses in the Netherlands

The last couple of days I read a number of times about stabilization in house prices which had been dropping due to the crisis. And you get hit by numbers such as change against Q2 2013 or Q3 2012. These are accompanied by reasons why this or that quarter may be special so changes may be off. To be...

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Influence Analysis for Repeated Measures Data

October 6, 2013
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Influence Analysis for Repeated Measures Data

I am trying exercise 59.8 (page 5057) of the SAS/STAT Users Guide 12.3 in R. The interesting thing is that influence is investigated on subject level rather than individual level. The diagnostics in nlme does not do leave-subject-out, at least, not tha...

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Mixed Models: Influence in Heterogeneous Variance Model

September 29, 2013
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Mixed Models: Influence in Heterogeneous Variance Model

In this post I extend my knowledge of mixed models by redoing section 59.7 (page 5048) of the SAS/STAT user guide. I don't think this particular example can be run in lme4, so that leaves nlme and MCMCglmm. MCMCglmm has less ability for influence measu...

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