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Using a boundary line approach to analyze N2O flux data from agricultural soils (2000)

Schmidt, Ulrich ; Thöni, Hanspeter ; Kaupenjohann, Martin

Springer

Nutrient cycling in agroecosystems 57 (2000), S. 119-129

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ISSN: 1573-0867

Keywords: boundary line ; field measurement ; model ; N2O flux

Source: Springer Online Journal Archives 1860-2000

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Abstract Predicting the N2O flux from soils is difficult because of the complex interplay of the various processes involved. In this study a boundary line approach was used to apply results from mechanistic experiments to N2O flux data resulting from measurements on field scale in southern Germany. Boundary lines were fitted to the rim of the data points in scattergrams depicting readily obtainable soil variables against the measured N2O flux. The boundary line approach is based on the hypothesis that this line depicts the functional dependency between the two variables. For determining these boundary lines a novel method was applied. The function best representing the relationship between the N2O flux and soil temperature had a maximum above 23 °C and the one between the N2O flux and the water filled pore space (WFPS, to represent water content) had a maximum at 72% WFPS. In the range of 0–20 mg N kg-1 the relationship between N2O flux and nitrate in the soil was best described by a linear function, whereas in the range of 0–35 mg N kg-1 a Michaelis–Menten function was more appropriate. The boundary lines specified in this study are in agreement with existing theoretical concepts as well as experimental results obtained under controlled and field conditions as reported in the literature. Therefore, the boundary line approach can be used to improve empirical models for predicting the N2O flux in the field.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1009854220769

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Equilibrium Bidding without the Independence Axiom: A Graphical Analysis (2000)

Grimm, Veronika ; Schmidt, Ulrich

Springer

Theory and decision 49 (2000), S. 361-374

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ISSN: 1573-7187

Keywords: Auctions ; Non-expected utility

Source: Springer Online Journal Archives 1860-2000

Topics: Sociology , Economics

Notes: Abstract In this paper we examine optimal bidding without the independence axiom in a unified framework which allows for a clear graphical representation. Thus, we can show very simply the independence axiom to be a necessary and sufficient condition on preferences for strategical equivalence of the two first-price and second-price auctions, respectively, and for the second-price sealed-bid auction to be demand revealing. The analysis reveals that the betweenness property is necessary and sufficient for the ascending-bid auction to be demand revealing while optimal bids exceed (are less than) bidders' valuations, iff preferences are quasiconcave (quasiconvex). Furthermore, it can be shown that fanning out (fanning in) leads to a higher (lower) selling-price in open than in sealed-bid auctions.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1026585831556

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Certainty preference and the Arrow-Pratt measure (2000)

Schmidt, Ulrich

Springer

OR spectrum 22 (2000), S. 347-359

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ISSN: 1436-6304

Keywords: Key words: Certainty effect – risk aversion – Arrow-Pratt measure – Non-expected utility theory ; Schlüsselwörter: Sicherheitseffekt – Risikoaversion – Arrow-Pratt Maß– Nicht-lineare Nutzentheorie

Source: Springer Online Journal Archives 1860-2000

Topics: Mathematics , Economics

Description / Table of Contents: Zusammenfassung. In Schmidt (1998) wurde ein neues Modell des Entscheidungsverhaltens unter Risiko axiomatisiert, das den Sicherheitseffekt abbilden kann, gleichzeitig aber äquivalent zum Erwartungsnutzen in allen anderen Entscheidungssituationen ist. Dieses Modell, das als Erwartungsnutzen mit Sicherheitspräferenz bezeichnet wird, erlaubt eine Messung des Sicherheitseffektes analog zur Messung von Risikoaversion durch das Arrow-Pratt Maß. Das Ziel des vorliegenden Beitrages ist eine umfassende Charakterisierung der Sicherheitspräferenz. Dazu werden u.a. alle wesentlichen Konzepte der Theorie der Risikoaversion im Rahmen der Sicherheitspräferenz definiert und analysiert. Insgesamt zeigt sich, daß die Messung der Sicherheitspräferenz die selben theoretischen Möglichkeiten aufweist wie die Messung der Risikoaversion durch das Arrow-Pratt Maß. Weiterhin wird der Erwartungsnutzen mit Sicherheitspräferenz in die existierende Literatur zu nicht-linearen Nutzentheorien eingeordnet.

Notes: Abstract. In Schmidt (1998) a new axiomatic model of decision making under risk has been developed, which can accommodate the certainty effect and is, apart from this property, equivalent to expected utility in all other choice problems. A central feature of this model, termed expected utility with certainty preference, is to allow for a measurement of the certainty effect analogously to the measurement of risk aversion by the Arrow-Pratt measure. The purpose of the present paper is to provide a complete characterization of certainty preference. Therefore, among other things, all standard concepts in the theory of risk aversion are defined and analyzed in the framework of certainty preference. This investigation reveals that the measurement of the certainty effect has the same theoretical capabilities as the measurement of risk aversion by the Arrow-Pratt measure. Additionally, expected utility with certainty preference is compared with the existing literature on non-expected utility models.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/PL00013337

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