An alternative approach to the analysis of mixed cropping experiments. 1. Estimation of competition effects.

A simple model is introduced to estimate the degree of intra-specific and inter-specific competition and niche differentiation from final biomass data of a set of populations varying in spp. composition and total density. Competition effects can be estimated using addition series. The model is illustrated with results from mixed cropping of maize and groundnut. (Abstract retrieved from CAB Abstracts by CABI’s permission)

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An alternative approach to the analysis of mixed cropping experiments. 2. Marketable yield.

Netherlands Journal of Agricultural Science ◽

10.18174/njas.v31i2.16954 ◽

1983 ◽

Vol 31 (2) ◽

pp. 143-155

Author(s):

C.J.T. Spitters

Keyword(s):

Harvest Index ◽

Plant Biomass ◽

Niche Differentiation ◽

Individual Plant ◽

Mixed Cropping ◽

Resource Exploitation ◽

Marketable Yield ◽

Land Equivalent Ratio ◽

Alternative Approach ◽

Competition Effects

The effects of competition on marketable yield are derived from those on biomass by means of the relation between individual plant biomass and harvest index. A method is presented to estimate competition effects and advantage of mixed cropping directly from the data of marketable yield. The effect of spp. composition and population density on the advantage of mixed cropping, measured by the land equivalent ratio, is partitioned into an effect due to better resource exploitation (niche differentiation), a favourable influence of mixed cropping on harvest index and an effect due to density which can also be achieved by growing monocrops at a higher density. The approach is illustrated with the results of an experiment on mixed cropping of maize and groundnuts. (Abstract retrieved from CAB Abstracts by CABI’s permission)

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Deliberate Product Definition: Customizing the Product Definition Process

Journal of Marketing Research ◽

10.1177/002224379703400207 ◽

1997 ◽

Vol 34 (2) ◽

pp. 276-285 ◽

Cited By ~ 9

Author(s):

G. Kalyanaram ◽

V. Krishnan

Keyword(s):

Simple Model ◽

Product Development ◽

Development Process ◽

Product Development Process ◽

Just In Time ◽

Customer Preferences ◽

Market Launch ◽

Alternative Approach ◽

Product Specifications ◽

Product Definition

The process of product definition, during which a firm establishes the product specifications, has a vital influence on the success of a product but has attracted little attention from researchers. Conventional wisdom stipulates that a firm should finalize its specifications early in the product development process. However, in industries facing rapid technological change, stiff competition, and uncertain customer needs, specifications set too early could become outdated by the time of market launch, thereby decreasing the product's benefits to the customer. The authors discuss an alternative approach, in which a firm delays commitment to product specifications and finalizes them just in time for the market launch after careful deliberation, thereby benefiting from the evolution of core technologies and customer preferences. Because such an approach introduces new managerial challenges, it would be appropriate only under certain circumstances. The authors develop a simple model of the product definition process that offers insights about how a firm should customize the process to suit its needs. They capture these insights as a managerial framework and illustrate them with industry examples involving the development process for laser printers and network test kits.

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A simple model of magnetospheric trough total density

Journal of Geophysical Research Atmospheres ◽

10.1029/97ja03665 ◽

1998 ◽

Vol 103 (A5) ◽

pp. 9293-9297 ◽

Cited By ~ 20

Author(s):

D. L. Gallagher ◽

P. D. Craven ◽

R. H. Comfort

Keyword(s):

Simple Model ◽

Total Density

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Top-down transformation choice

Statistical Modelling ◽

10.1177/1471082x17748081 ◽

2018 ◽

Vol 18 (3-4) ◽

pp. 274-298 ◽

Cited By ~ 5

Author(s):

Torsten Hothorn

Keyword(s):

Simple Model ◽

Distribution Functions ◽

Model Fit ◽

Transformation Models ◽

Constant Variance ◽

Alternative Approach ◽

Complex Models ◽

Interpretable Models ◽

The Impact ◽

Simple Models

Simple models are preferred over complex models, but over-simplistic models could lead to erroneous interpretations. The classical approach is to start with a simple model, whose shortcomings are assessed in residual-based model diagnostics. Eventually, one increases the complexity of this initial overly simple model and obtains a better-fitting model. I illustrate how transformation analysis can be used as an alternative approach to model choice. Instead of adding complexity to simple models, step-wise complexity reduction is used to help identify simpler and better interpretable models. As an example, body mass index (BMI) distributions in Switzerland are modelled by means of transformation models to understand the impact of sex, age, smoking and other lifestyle factors on a person's BMI. In this process, I searched for a compromise between model fit and model interpretability. Special emphasis is given to the understanding of the connections between transformation models of increasing complexity. The models used in this analysis ranged from evergreens, such as the normal linear regression model with constant variance, to novel models with extremely flexible conditional distribution functions, such as transformation trees and transformation forests.

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A simple model of network formation with competition effects

Journal of Mathematical Economics ◽

10.1016/j.jmateco.2021.102611 ◽

2021 ◽

pp. 102611

Author(s):

Timo Hiller

Keyword(s):

Simple Model ◽

Network Formation ◽

Competition Effects

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Competition effects with mixed stands of wheat and kochia (Kochia scoparia) biotypes resistant and susceptible to acetolactase synthase inhibitor herbicides

Scientia Agricola ◽

10.1590/s0103-90161994000200008 ◽

1994 ◽

Vol 51 (2) ◽

pp. 245-251 ◽

Cited By ~ 2

Author(s):

P.J. Christoffoleti ◽

P. Westra

Keyword(s):

Interspecific Competition ◽

Competitive Ability ◽

Wheat Plant ◽

Niche Differentiation ◽

Kochia Scoparia ◽

Replacement Series ◽

Mixed Stands ◽

Competition Effects ◽

Synthase Inhibitor ◽

Differentiation Index

Greenhouse experiments were conducted to compare the competitive ability of sulfonylurea resistant and susceptible kochia (Kochia scoparia L. Schard) compared to wheat. The results of several replacement series experiments indicate that wheat was the dominant competitor, and an average of one wheat plant reduced resistant kochia yield per plant equal to the effect of 4.8 resistant kochia or 5.4 susceptible kochia plants. Intraspeciflc competition was more important than interspecific competition for wheat, whereas the reverse was true for the resistant and susceptible kochia. The results of the niche differentiation index (NDI) indicate that wheat and either resistant or susceptible kochia are only partly limited by the same resources. The resistant and susceptible kochia, however, are limited by the same resources.

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