Dealing with Zeros

Martín‐Fernández, Josep Antoni; Palarea‐Albaladejo, Javier; Olea, Ricardo A.

doi:10.1002/9781119976462.ch4

Cited by 120 publications

(113 citation statements)

References 14 publications

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“…The ilr transformations, as well as ilr back-transformations to familiar concentration units, were computed using the R "compositions" package [50]. Some B and Cu levels below detection limits were replaced by the detection limit of the equipment for the corresponding element, multiplied by 0.65 [51]. Tukey's test (p ≤ 0.05) allowed detecting significant difference between TN and TP populations.…”

Section: Discussionmentioning

confidence: 99%

Mineral Balance Plasticity of Cloudberry (<i>Rubus chamaemorus</i>) in Quebec-Labrador Bogs

Parent¹,

Parent²,

Hébert-Gentile³

et al. 2013

AJPS

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The "ionome", or plant elemental signature, is the elemental composition of an organisms, that may vary with genotypic traits and phenotypic plasticity. Cloudberry (Rubus chamaemorus L.) is a circumboreal wild berry naturally growing in oligotrophic oceanic bogs of Quebec and Labrador. Our objective was to relate cloudberry stand productivity to the ionomes of female ramets and explore the cause of nutrient imbalance in low-performing stands. We analyzed 13 elements in female ramets collected in 86 natural sites where crop productivity varied widely. We computed orthogonally arranged balances reflecting plant stoichiometric rules and soil biogeochemistry. Balances were expressed as isometric log ratios (ilr) between ad hoc sub-compositions. Balances were synthesized into a Mahalanobis distance optimized based on receiving operating characteristics (ROC). The critical Mahalanobis distance was found to be 5.29 for cutoff berry yield of 3.8 g·m −2 with test performance of 0.88, as measured by the area under the ROC curve. Although past research on cloudberry focused mainly on the N/P ratio, this exploratory mineral balance analysis indicated that imbalance in the [P,N | S,C] and [Al | Nutrients] partitions appeared to be the factors limiting the most cloudberry productivity in the bogs. Some highly productive stands showed relatively high C fixation and K use efficiency. Due to the complexity of interactions, diagnosis should be conducted computing first a global imbalance index (Mahalanobis distance), then examining in the balance domain binary partitions departing most from reference, and finally appreciating relative shortage, sufficiency or excess of elements in the concentration domain.

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Section: Discussionmentioning

confidence: 99%

Mineral Balance Plasticity of Cloudberry (<i>Rubus chamaemorus</i>) in Quebec-Labrador Bogs

Parent¹,

Parent²,

Hébert-Gentile³

et al. 2013

AJPS

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“…Simulations show this method performs particularly well if the proportion of zeros is below 10% (Martín-Fernández et al, 2011). In our data set, zeros were present only in one budget category (discretionary expenditure).…”

Section: Martínmentioning

confidence: 93%

Determinants in Tourist Expenditure Composition — The Role of Airline Types

2015

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The reduction in transportation costs when travelling with a low-cost airline (LCA) seems to have modified the composition of the trip budget. An understanding of expenditure composition when comparing LCA and legacy airline travellers is vital for destination marketers. Using micro official statistics data for air travellers to Spain in 2010 and the compositional data analysis (CODA) methodology, this study analyses the determinants of trip budget composition and its differences between airline types. The authors consider transportation expenses, as well as basic (accommodation and food) and discretionary (activities, shopping, etc) at-destination expenses. Log-ratios of budget share are fitted to a MANOVA, with travellers' attributes as explanatory factors along with the moderating effect of the airline type. Among the findings are that high-income LCA travellers spend relatively more at the destination, LCA touristsThe authors are pleased to acknowledge the support of the Spanish Institute of Tourism Studies (Instituto de Estudios Turísticos) in providing them with the raw data.

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“…If the z vector contains zeros, they must be replaced beforehand (Martín-Fernández et al, 2011). When, like in this case, the data are counts of frequencies, the common framework for replacing the zeros is the Bayesian-multiplicative approach (Martín-Fernández et al, 2015b;Pierotti et al, 2009) In the BayesLaplace's rule, the z cero values are replaced with:…”

Section: Zero Replacementmentioning

confidence: 99%

Compositional visualization of intermedia agenda setting by the main media groups and political parties in the Spanish 2015 General Elections

Duatis¹,

Coenders²,

Sáez³

2018

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This article presents the compositional biplot as an innovative methodological approach to visualise intermedia agenda-setting in the study of media and political agendas in an intuitive way. As an illustration, we use a content analysis of the main Spanish media groups (RTVE, Prisa, Vocento, Unidad Editorial, COPE, Atresmedia, Planeta, Godó, Mediaset España and Libertad Digital) and political parties with a sole constituency (Partido Popular, Partido Socialista Obrero Español, Podemos, Ciudadanos and Izquierda Unida) within the framework of the 2015 Spanish general election period. Unlike traditional approaches, compositional analysis in general and the biplot in particular emphasize the relative salience of the contents within the agenda. The visualisation confirms the methodological soundness of the approach, while also providing a novel perspective of the case under study and visualizing the representation of intermedia agenda-setting.

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Dealing with Zeros

Cited by 120 publications

References 14 publications

Mineral Balance Plasticity of Cloudberry (<i>Rubus chamaemorus</i>) in Quebec-Labrador Bogs

Mineral Balance Plasticity of Cloudberry (<i>Rubus chamaemorus</i>) in Quebec-Labrador Bogs

Determinants in Tourist Expenditure Composition — The Role of Airline Types

Compositional visualization of intermedia agenda setting by the main media groups and political parties in the Spanish 2015 General Elections

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Dealing with Zeros

Cited by 120 publications

References 14 publications

Mineral Balance Plasticity of Cloudberry (&lt;i&gt;Rubus chamaemorus&lt;/i&gt;) in Quebec-Labrador Bogs

Mineral Balance Plasticity of Cloudberry (&lt;i&gt;Rubus chamaemorus&lt;/i&gt;) in Quebec-Labrador Bogs

Determinants in Tourist Expenditure Composition — The Role of Airline Types

Compositional visualization of intermedia agenda setting by the main media groups and political parties in the Spanish 2015 General Elections

Contact Info

Product

Resources

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Mineral Balance Plasticity of Cloudberry (<i>Rubus chamaemorus</i>) in Quebec-Labrador Bogs

Mineral Balance Plasticity of Cloudberry (<i>Rubus chamaemorus</i>) in Quebec-Labrador Bogs