Average Marginal Income Tax Rates in New Zealand, 1907-2009

Estimates of marginal tax rates (MTRs) faced by individual economic agents, and for various aggregates of taxpayers, are important for economists testing behavioural responses to changes in those tax rates. This paper reports estimates of a number of personal marginal income tax rate measures for New Zealand since 1907, focusing mainly on the aggregate income-weighted average MTRs proposed by Barro and Sahasakul (1983, 1986) and Barro and Redlick (2011). The paper describes the methodology used to derive the various MTRs from original data on incomes and taxes from Statistics New Zealand Official Yearbooks (NZOYB), and discusses the resulting estimates

Genome-wide analyses of the Bemisia tabaci species complex reveal contrasting patterns of admixture and complex demographic histories.

Once considered a single species, the whitefly, Bemisia tabaci, is a complex of numerous morphologically indistinguishable species. Within the last three decades, two of its members (MED and MEAM1) have become some of the world's most damaging agricultural pests invading countries across Europe, Africa, Asia and the Americas and affecting a vast range of agriculturally important food and fiber crops through both feeding-related damage and the transmission of numerous plant viruses. For some time now, researchers have relied on a single mitochondrial gene and/or a handful of nuclear markers to study this species complex. Here, we move beyond this by using 38,041 genome-wide Single Nucleotide Polymorphisms, and show that the two invasive members of the complex are closely related species with signatures of introgression with a third species (IO). Gene flow patterns were traced between contemporary invasive populations within MED and MEAM1 species and these were best explained by recent international trade. These findings have profound implications for delineating the B. tabaci species status and will impact quarantine measures and future management strategies of this global pest

Una Teoría Positiva de Política Monetaria en un Modelo de Tasa Natural

A discretionary policymaker can create surprise inflation, which may reduce unemployment and raise government revenue. But when people understand the policymaker's objectives, these surprises cannot occur systematically. In equilibrium people form expecta

Endogenous growth and property rights over renewable resources

We study how different regimes of access rights to renewable natural resources - namely, open access versus full property rights – affect sustainability, growth and welfare in the context of modern endogenous growth theory. Resource exhaustion may occur under both regimes but is more likely to arise under open access. Moreover, under full property rights, positive resource rents increase expenditures on manufacturing goods and temporarily accelerate productivity growth, but also yield a higher resource price at least in the short-to-medium run. We characterize analytically and quantitatively the model’s dynamics to assess the welfare implications of differences in property rights enforcement

Explaining productivity in a poor productivity region

© 2017, © The Author(s) 2017. Productivity is the preferred measure of firm-level efficiency and perceived to reflect resource use rates. Semi-structured interviews with restaurant managers in a tourism-dominated low productivity rural area reveal that they are motivated to supply products that they believe in and to sustain a quality of life that meets their needs rather than striving to achieve higher productivity. Pricing strategies, managerial objectives and local market characteristics are found to radically influence the area’s productivity value. An area’s productivity value might not be an indicator of resource use rates or productive efficiency, and could instead reflect resident managers’ motivations towards money and the presence of opportunities to achieve scale economies