Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

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An uncertain climate : the value of uncertainty and sensitivity analysis in environmental impact assessment of food
Groen, E.A. - \ 2016
University. Promotor(en): Imke de Boer, co-promotor(en): Eddy Bokkers; R. Heijungs. - Wageningen : Wageningen University - ISBN 9789462577558 - 239 p.
environment - environmental impact - climatic change - uncertainty analysis - screening - sensitivity analysis - modeling - greenhouse gases - farms - dairy farms - food production - correlation analysis - milieu - milieueffect - klimaatverandering - onzekerheidsanalyse - screenen - gevoeligheidsanalyse - modelleren - broeikasgassen - landbouwbedrijven - melkveebedrijven - voedselproductie - correlatieanalyse

ABSTRACT

Production of food contributes to climate change and other forms of environmental impact. Input data used in environmental impact assessment models, such as life cycle assessment (LCA) and nutrient balance (NB) analysis, may vary due to seasonal changes, geographical conditions or socio-economic factors (i.e. natural variability). Moreover, input data may be uncertain, due to measurement errors and observational errors that exist around modelling of emissions and technical parameters (i.e. epistemic uncertainty). Although agricultural activities required for food production are prone to natural variability and epistemic uncertainty, very few case studies in LCA and NB analysis made a thorough examination of the effects of variability and uncertainty. This thesis aimed to enhance understanding the effects of variability and uncertainty on the results, by means of uncertainty and sensitivity analysis. Uncertainty analysis refers to the estimation of the uncertainty attribute of a model output using the uncertainty attributes of the model in- puts. There are three types of sensitivity analyses: (I) a local sensitivity analysis addresses what happens to the output when input parameters are changed, i.e. the intrinsic model behaviour of a parameter; (II) a screening analysis addresses what happens to the output based on the un- certainty range of the different input parameters; and (III) a global sensitivity analysis addresses how much the uncertainty around each input parameter contributes to the output variance. Both the screening analysis and the global sensitivity analysis combine the intrinsic model behaviour with the information of uncertainty around input parameters. Applying uncertainty analysis and sensitivity analysis can help to reduce the efforts for data collection, support the development of mitigation strategies and improve overall reliability, leading to more informed decision making in environmental impact assessment models. Including uncertainty in environmental impact assessment models showed that: (1) the type of uncertainty analysis or sensitivity analysis applied depends on the question to be addressed and the available information; (2) in some cases it is no longer possible to benchmark environmental performance if epistemic uncertainty is included; (3) including correlations between input parameters during uncertainty propagation will either increase or decrease output variance, which can be predicted beforehand; (4) under specific characteristics of the input parameters, ignoring correlation has a minimal effect on the model outcome. Systematically combining a local and global sensitivity analysis in environmental impact assessment models: (1) resulted in more parameters than found previously in similar studies (for the case studies discussed in this thesis); (2) allowed finding mitigation options, either based on innovations (derived from the local sensitivity analysis) or on management strategies (derived from the global sensitivity analysis); (3) showed for which parameters reliability should be improved by increasing data quality; (4) showed that reducing the (epistemic) uncertainty of the most important parameters can affect the comparison of the environmental performance.

Inventarisatie omstandigheden optreden zwarte vlekken in peen : analyse praktijkmonsters 2008 t/m 2010
Schepers, H.T.A.M. ; Spruijt-Verkerke, J. ; Berg, W. van den - \ 2011
Lelystad : PPO AGV - 28
daucus carota - penen - plantenziekten - plantenziekteverwekkende schimmels - cultuurmethoden - risicofactoren - oogstfactoren - correlatieanalyse - carrots - plant diseases - plant pathogenic fungi - cultural methods - risk factors - yield factors - correlation analysis
Zwarte vlekken in peen kan bij zowel gangbare als biologisch geteelde peen grote schade veroorzaken (BioKennis bericht, 2007). Een complex van omstandigheden waaronder de aanwezigheid van diverse schimmels in de grond, de groeiomstandigheden van het gewas, de oogstomstandigheden en de bewaarcondities spelen bij het optreden een rol. Een inventarisatie van allerlei omstandigheden in 2001- 2003 leverde indicaties op dat slechte oogstomstandigheden de grootste risicofactor vormen. Onderzoek met een extreem zware kunstmatig aangebrachte ziektedruk liet ook zien dat afhankelijk van de schimmel een wondhelingsperiode van één week enig positief effect had (Wander, Meier, Booij & Velema, 2006). Bij de huidige praktijk waarbij grote hoeveelheden kisten bij één bewaarregime worden bewaard is het differentiëren van bewaarregimes niet mogelijk. Tot op heden zijn er dus nog geen praktisch uitvoerbare maatregelen die een duidelijk effect op zwarte vlekken hebben. In opdracht van het Productschap Tuinbouw is een correlatie analyse uitgevoerd om na te gaan of er een verband is tussen teeltfactoren en het al dan niet voorkomen van zwarte vlekken in de jaren 2008 t/m 2010 in de praktijk.
Multidimensional Scaling with Regional Restrictions for Facet Theory: an Application to Levi's Political Protest Data
Groenen, P.J.F. ; Lans, I.A. van der - \ 2006
Rotterdam : RSM Erasmus Univ., Erasmus Research Inst. Management (ERIM) (ERIM report series research in management ERS-2006-057-MKT) - 20
schaalverandering - dimensie-analyse - wiskundige modellen - algoritmen - vergelijkingen (wiskundig) - correlatieanalyse - classificatie - scaling - dimensional analysis - mathematical models - algorithms - equations - correlation analysis - classification
Multidimensional scaling (MDS) is often used for the analysis of correlation matrices of items generated by a facet theory design. The emphasis of the analysis is on regional hypotheses on the location of the items in the MDS solution. An important regional hypothesis is the axial constraint where the items from different levels of a facet are assumed to be located in different parallel slices. The simplest approach is to do an MDS and draw the parallel lines separating the slices as good as possible by hand. Alternatively, Borg and Shye (1995) propose to automate the second step. Borg and Groenen (1997, 2005) proposed a simultaneous approach for ordered facets when the number of MDS dimensions equals the number of facets. In this paper, we propose a new algorithm that estimates an MDS solution subject to axial constraints without the restriction that the number of facets equals the number of dimensions. The algorithm is based on constrained iterative majorization of De Leeuw and Heise...
Relationship between variation in quality of individual seeds and bulk seed quality in common bean (Phaseolus vulgaris L.) seed lots
Muasya, R.M. ; Lommen, W.J.M. ; Auma, E.O. ; Struik, P.C. - \ 2006
NJAS Wageningen Journal of Life Sciences 54 (2006)1. - ISSN 1573-5214 - p. 5 - 16.
phaseolus vulgaris - peulvruchten - zaadkwaliteit - gewaskwaliteit - kieming - levensvatbaarheid - elektrische geleidbaarheid - statistiek - gemiddelden - statistische analyse - variantie-analyse - correlatieanalyse - grain legumes - seed quality - crop quality - germination - viability - electrical conductivity - statistics - averages - statistical analysis - analysis of variance - correlation analysis - pod fractions - maturity - growth - vigor - crops
The variation in individual seed electrical conductivity (EC) (µS cm¿¹ g¿¹) of 24 seed lots of two common bean cultivars produced at two locations was quantified using the parameters mean ¿ median, standard deviation (SD), and the range 0¿75%. Also coefficient of variation (CV) was tested, which was regarded not to be a good indicator of this type of variation. Bulk seed lot quality of this material with a very high germination percentage was determined using EC and percentage viable seeds. At physiological maturity (PM), a low variation in individual seed EC as quantified by mean ¿ median, SD and the range 0¿75% was associated with good quality as measured by a low bulk EC and a high percentage of viable seeds. At harvest maturity, associations were less clear than at PM, partly because individual seed variation was smaller and also because bulk EC values differed only slightly among most seed lots. The relationships between individual seed variation and bulk quality were different for the two sites, as shown by a statistically significant improvement of the adjusted R² of the regression when site was included in the regression model, but the relationships were not affected by cultivar. No relationship was found between CV for individual seed EC and bulk quality.
Market Orientation, Product Innovation and Market Performance : the Case of Small Independent Companies
Verhees, F.J.H.M. - \ 1999
Tijdschrift voor sociaalwetenschappelijk onderzoek van de landbouw 14 (1999)1. - ISSN 0921-481X - p. 19 - 35.
kleine bedrijven - productontwikkeling - innovaties - nieuwe producten - marktregulaties - snijbloemen - rosa - correlatieanalyse - regressieanalyse - small businesses - product development - innovations - new products - market regulations - cut flowers - correlation analysis - regression analysis
Een wijze van marktorientering voor kleine bedrijven is bestudeerd en wordt hier uitgelegd, waarbij als praktijkvoorbeeld de (positieve) invloed bij Nederlandse rozenkwekers is nagegaan
DNA-patroon en toeristisch gedrag: een multidisciplinaire sprong
Elands, B. ; Sandbrink, H. ; Vries, S. de - \ 1999
Wageningen : Landbouwuniversiteit [etc,] - ISBN 9789067545648 - 29
vrijetijdsactiviteiten - besluitvorming - vrijetijdsgedrag - correlatieanalyse - productontwikkeling - consumentengedrag - regionale ontwikkeling - patroonherkenning - leisure activities - decision making - leisure behaviour - correlation analysis - product development - consumer behaviour - regional development - pattern recognition
Effects of road density; a case study of the moor frog.
Vos, C.C. - \ 1997
In: Habitat fragmentation & infrastructure : proceedings of the international conference "Habitat fragmentation, infrastructure and the role of ecological engineering", 17 - 21 September 1995, Maastricht - The Hague, The Netherlands. - - p. 93 - 97.
verkeer - verkeerspatronen - dichtheid - capaciteit - tellen - onderzoek - dieren - territorium - habitats - milieu - anura - kikkers - padden - multivariate analyse - correlatieanalyse - regressieanalyse - nadelige gevolgen - milieueffect - menselijke activiteit - traffic - traffic patterns - density - capacity - counting - research - animals - territory - environment - frogs - toads - multivariate analysis - correlation analysis - regression analysis - adverse effects - environmental impact - human activity
Versnippering
Population growth, income distribution and economic development - theory, methodology, and empirical results.
Heerink, N. - \ 1993
Berlin : Springer Verlag - ISBN 9783540573234 - 401
correlatieanalyse - demografie - econometrische modellen - econometrie - economische ontwikkeling - bevolking - inkomen - inkomensverdeling - wiskundige modellen - multivariate analyse - populatiegroei - regressieanalyse - statistiek - theorie - vermogensverdeling - correlation analysis - demography - econometric models - econometrics - economic development - human population - income - income distribution - mathematical models - multivariate analysis - population growth - regression analysis - statistics - theory - wealth distribution
Regressieanalyse op basis van een gestratificeerde steekproef
Elhorst, J.P. - \ 1988
Den Haag : L.E.I. (Onderzoekverslag / Landbouw-Economisch Instituut, Afdeling Landbouw no. 36) - 47
correlatieanalyse - multivariate analyse - regressieanalyse - bemonsteren - correlation analysis - multivariate analysis - regression analysis - sampling
Om de ontwikkelingen in de Nederlandse landbouw te kunnen volgen houdt het LEI boekhoudingen bij van ruim 1000 landbouwbedrijven. Deze bedrijven worden gekozen op basis van een steekproef uit de in de Landbouwtelling geregistreerde bedrijven. Om tot een zo getrouw mogelijke afspiegeling te komen van de Nederlandse landbouw dient de samenstelling van de steekproef zoveel mogelijk overeen te komen met die van de gehele populatie. Door een tweetal maatregelen wordt getracht de kans op afwijkingen door onder- of oververtegenwoordiging te verkleinen. Ten eerste wordt de steekproef gestratificeerd: de samenstelling ervan wordt gereguleerd via een onderverdeling in strata en het trekken daaruit van afzonderlijke steekproeven. Ten tweede wordt binnen deze strata rekening gehouden met de grootte van de onderlinge verschillen tussen de bedrijven door het steekproefpercentage te varieren. De juistheid van de keuze van deze maatregelen ter verkleining van de afwijkingen wordt in het verslag beoordeeld
On a test for the difference between two correlation coefficients
Corsten, L.C.A. - \ 1970
Wageningen : Veenman (Mededelingen / Landbouwhogeschool 70-13) - 21
multivariate analyse - correlatieanalyse - regressieanalyse - multivariate analysis - correlation analysis - regression analysis
Vectors, a tool in statistical regression theory
Corsten, L.C.A. - \ 1958
Landbouwhogeschool Wageningen. Promotor(en): N.H. Kuiper. - Wageningen : Veenman - 92
correlatieanalyse - regressieanalyse - correlation analysis - regression analysis
Using linear algebra this thesis developed linear regression analysis including analysis of variance, covariance analysis, special experimental designs, linear and fertility adjustments, analysis of experiments at different places and times. The determination of the orthogonal projection, yielding efficient unbiased estimates and playing a dominant role in statistical tests, was extensively considered, in particular by iterative time-saving procedures based on geometrical considerations and on power-series expansions. Subspaces were systematically introduced for levels, for main effects and for interactions. This allowed a general interpretation of orthogonality of classifications. This introduction of subspaces also permitted the simultaneous account of orthogonal polynomia in one or more variables with concurrent classifications. Designs such as balanced and partially balanced incomplete block designs, as lattices and as Latin squares could be characterized by fixed angles between spaces or between physically meaningful subspaces of these effect spaces. The missing-plot technique was developed in a more general and simple form. Finally, estimation and testing problems were discussed for several non-orthogonal classifications, of which one or more had random effects or interactions. This included recovery of inter-block information, and analysis of split- plot designs and series of experiments.<p/>
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