Hooiveld, Guido
2014-May-02 13:21 UTC
[R] package for 'positive' incremental AUC determination?
Hello, I am analyzing a dataset that is comprised of sequential measurements in plasma glucose levels after consumption of different food stuffs by multiple subjects. I would like to determine the so-called glycemic index, i.e. the area over the baseline (=fasting glucose level) under the curve, ignoring area beneath the baseline (the 'positive' incremental AUC). [see attached PDF, alternatively Figure 11c in http://dx.doi.org/10.1079/NRR2005100]. Ideally, significance of the difference of the positive iAUC between treatments as well as the time point of the maximum plasma glucose level for each treatment are also reported. I know of the function auc() in the package "PK", which in principle can be used to calculate the incremental AUC, but unfortunately it cannot ignore the area beneath the baseline nor does it provide info on differences between the time point of the (glucose) peak. Therefore any pointer is appreciated! Guido --------------------------------------------------------- Guido Hooiveld, PhD Nutrition, Metabolism & Genomics Group Division of Human Nutrition Wageningen University Biotechnion, Bomenweg 2 NL-6703 HD Wageningen the Netherlands tel: (+)31 317 485788 fax: (+)31 317 483342 email: guido.hooiveld at wur.nl internet: http://nutrigene.4t.com http://scholar.google.com/citations?user=qFHaMnoAAAAJ http://www.researcherid.com/rid/F-4912-2010 -------------- next part -------------- A non-text attachment was scrubbed... Name: pos_iAUC_method.pdf Type: application/pdf Size: 74781 bytes Desc: pos_iAUC_method.pdf URL: <https://stat.ethz.ch/pipermail/r-help/attachments/20140502/57f8ad8d/attachment.pdf>