Change search
ReferencesLink to record
Permanent link

Direct link
NOPAPROD non-parametric testing on projections from multivariate data: Applications to near infrared spectroscopy in clinical studies
Umeå University, Faculty of Science and Technology, Department of Chemistry.
Umeå University, Faculty of Science and Technology, Department of Chemistry.
2009 (English)In: Journal of Near Infrared Spectroscopy, ISSN 0967-0335, Vol. 17, no 2, 101-107 p.Article in journal (Refereed) Published
Abstract [en]

Clinical studies may be carried out using non-invasively collected near infrared spectra of patient skin. Two problems encountered are: (1) data reduction to go from thousands of wavelengths to some clinically relevant estimator and (2) getting statistical significance from noisy data with sometimes very skewed distributions. The problem of data reduction can usually be solved by principal component analysis to get a few meaningful components. In the space spanned by these components, a direction of discrimination may have to be found, typically discrimination between treated and control. A visual difference in a score plot is often not enough; statistical significance has to be demonstrated. Once a univariate estimator is found, non-parametric testing can show significant differences, even if the data are noisy and have an unknown and skewed distribution. The NOPRAPOD method combines the actions of finding a direction in a reduced data space and performing the non-parametric significance testing by producing a disk of significance. Two examples are included. Example one is from a study of diabetes-related neuropathy where it is shown that significant differences show up in the NIR spectra. Example two is from a study of post-operative radiation treatment of breast cancer patients, where it is shown that radiation effects (erythema) and the effect of lotion can be determined with an indication of significance from the NIR spectra.

Place, publisher, year, edition, pages
IM Publications LLP , 2009. Vol. 17, no 2, 101-107 p.
Keyword [en]
non- parametric testing, principal component analysis, score plots, near infrared spectroscopy, clinical measurements, erythema, diabetes, NOPAPROD, disk of significance
National Category
Chemical Sciences
URN: urn:nbn:se:umu:diva-25248DOI: 10.1255/jnirs.831OAI: diva2:229210
Available from: 2009-08-11 Created: 2009-08-11 Last updated: 2012-08-16Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Nyström, JosefinaLindholm-Sethson, Britta
By organisation
Department of Chemistry
In the same journal
Journal of Near Infrared Spectroscopy
Chemical Sciences

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 54 hits
ReferencesLink to record
Permanent link

Direct link