This paper surveys the microfoundations, empirical evidence, and estimation issues underlying the aggregate matching function. There is no consensus yet on microfoundations but one is emerging on estimation. An aggregate, constant returns, Cobb-Douglas matching function with hires as a function of vacancies and unemployment has been successfully estimated for several countries. Recent work has utilized disaggregated data to go beyond aggregate estimates, with many refinements and suggestions for future research. The paper discusses spatial aggregation issues, and implications of on-the-job search and of the timing of stocks and flows for estimated matching functions.

/pdf/looking-into-the-black-box-a-survey-of-the-matching-function-1boerkl7oh.pdf

Looking into the Black Box: A Survey of the Matching Function

Transactions of the Institute of British Geographers

The spatial heterogeneity of populations and communities plays a central role in many ecological theories, for instance the theories of succession, adaptation, maintenance of species diversity, community stability, competition, predator-prey interactions, parasitism, epidemics and other natural catastrophes, ergoclines, and so on. This paper will review how the spatial structure of biological populations and communities can be studied. We first demonstrate that many of the basic statistical methods used in ecological studies are impaired by autocorrelated data. Most if not all environmental data fall in this category. We will look briefly at ways of performing valid statistical tests in the presence of spatial autocorrelation. Methods now available for analysing the spatial structure of biological populations are described, and illustrated by vegetation data. These include various methods to test for the presence of spatial autocorrelation in the data: univariate methods (all-directional and two-dimensional spatial correlograms, and two-dimensional spectral analysis), and the multivariate Mantel test and Mantel correlogram; other descriptive methods of spatial structure: the univariate variogram, and the multivariate methods of clustering with spatial contiguity constraint; the partial Mantel test, presented here as a way of studying causal models that include space as an explanatory variable; and finally, various methods for mapping ecological variables and producing either univariate maps (interpolation, trend surface analysis, kriging) or maps of truly multivariate data (produced by constrained clustering). A table shows the methods classified in terms of the ecological questions they allow to resolve. Reference is made to available computer programs.

/pdf/spatial-pattern-and-ecological-analysis-k1i43u2tl3.pdf

Spatial pattern and ecological analysis

This paper presents an overview of multi-agent system models of land-use/cover change (MAS/LUCC models). This special class of LUCC models combines a cellular landscape model with agent-based representations of decisionmaking, integrating the two components through specification of interdependencies and feedbacks between agents and their environment. The authors review alternative LUCC modeling techniques and discuss the ways in which MAS/LUCC models may overcome some important limitations of existing techniques. We briefly review ongoing MAS/LUCC modeling efforts in four research areas. We discuss the potential strengths of MAS/LUCC models and suggest that these strengths guide researchers in assessing the appropriate choice of model for their particular research question. We find that MAS/LUCC models are particularly well suited for representing complex spatial interactions under heterogeneous conditions and for modeling decentralized, autonomous decision making. We discuss a range of possible roles for MAS/LUCC models, from abstract models designed to derive stylized hypotheses to empirically detailed simulation models appropriate for scenario and policy analysis. We also discuss the challenge of validation and verification for MAS/LUCC models. Finally, we outline important challenges and open research questions in this new field. We conclude that, while significant challenges exist, these models offer a promising new tool for researchers whose goal is to create fine-scale models of LUCC phenomena that focus on human-environment interactions.

http://www.dpi.inpe.br/cursos/tutoriais/modelagem/referencias/agents_lucc_overview.pdf

Multi-Agent Systems for the Simulation of Land-Use and Land-Cover Change: A Review

A comprehensive archive of Australian rainfall and climate data has been constructed from ground-based observational data. Continuous, daily time step records have been constructed using spatial interpolation algorithms to estimate missing data. Datasets have been constructed for daily rainfall, maximum and minimum temperatures, evaporation, solar radiation and vapour pressure. Datasets are available for approximately 4600 locations across Australia, commencing in 1890 for rainfall and 1957 for climate variables. The datasets can be accessed on the Internet at http://www.dnr.qld.gov.au/silo. Interpolated surfaces have been computed on a regular 0.05° grid extending from latitude 10°S to 44°S and longitude 112°E to 154°E. A thin plate smoothing spline was used to interpolate daily climate variables, and ordinary kriging was used to interpolate daily and monthly rainfall. Independent cross validation has been used to analyse the temporal and spatial error of the interpolated data. An Internet based facility has been developed which allows database clients to interrogate the gridded surfaces at any desired location.

Using spatial interpolation to construct a comprehensive archive of Australian climate data

The paper presents multivariate analysis of the relationship of SME growth with the acquisition of external business advice, whilst controlling for the influence of SME characteristics of age, manufacturing/services, high technology, innovator, level of skill of the workforce, exporter and number of competitors. The relationship of external business advice with SME performance is statistically significant for only a small number of sources and fields. Obtaining external advice in fields such as business strategy and staff recruitment is associated with positive firm performance. The main positive relationships of advice and performance are dominated by private sector sources such as lawyers, suppliers, customers and business friends/relatives. Collaborative arrangements with suppliers nationally/internationally have a strong positive relationship with employment and turnover growth; collaboration with local suppliers has a strong positive relationship with growth in profitability. There is little evidence of statistically significant relationships between government-backed providers of business advice such as Business Link and firm performance.

SME Growth: The Relationship with Business Advice and External Collaboration

This paper reports new survey results on the extent, sourcing and impact of external business advice to SMEs in Britain. The survey, covering 2547 respondents, is the largest and most definitive assessment to date. Its results demonstrate the very wide extent of external advice: used by 95% of respondent SMEs, an increase from 85.8% in a similar survey in 1991. The analysis of the survey assesses sources of advice in terms of the level of trust that exists between the supplier and the SME client. The market appears to be strongly segmented and dominated by high trust specialist sources (accountants, lawyers), customers, suppliers and business friends. Business associations and government-backed sources play an important but lesser role. The recent government initiative of Business Link has, however, established an important market, used by 27% of respondents. Impact assessments confirm the significance of high trust private sector suppliers for the most crucial supplies of advice. Variations in use occur ...

The use of external business advice by SMEs in Britain

Purpose – Aims to provide an assessment of the role of external business advice for small to medium‐sized enterprises (SMEs), comparing “soft” outcomes (improved ability to manage, ability to cope), “hard” outcomes (profitability, turnover, reduced costs), and overall satisfaction levels.Design/methodology/approach – A telephone survey using a stratified random sample frame provides a representative sample that allows comparison of the benefits of advice to SMEs in different size categories.Findings – The paper demonstrates a large and varied supply of advice with no evidence of reluctance by owners/managers to seek advice. “Hard” and “soft” outcomes tend to be combined for many SMEs, but the widest effects of external advice seem to be intangible, such as reassurance or reducing uncertainty. There is less variation between SMEs of different size than expected, but strong variation between types of external suppliers of advice. The level of regulation of suppliers and extent of their reputation or brand a...

The benefits of external support to SMEs: “Hard” versus “soft” outcomes and satisfaction levels

I examine the evolution of British government support to small and medium-sized enterprises (SMEs), using results from four waves of survey evidence in 1991, 1997, 2002, and 2004, and comparison wi...

SME Policy Support in Britain since the 1990s: What have We Learnt?:

BENNETT R. J. and ROBSON P. J. A. (2003) Changing use of external business advice and government supports by SMEs in the 1990s, Reg. Studies 37 , 795-811. This paper uses cross-sectional surveys of 1991 and 1997, a panel survey of firms surviving between 1991 and 1997 and comparison with a further cross-sectional survey in 1999, to compare the levels of use by SMEs of external business advice. The resource-based theory of the firm indicates that SMEs seek advice in order to increase their competitive capacity. Over time, increasing competition between SMEs is expected to lead to increasing use of advice. However, the paper demonstrates that only modest changes over time have occurred in aggregate use of external advice by SMEs, and these are not statistically significant. This suggests that earlier growth in external business advice services may now have plateaued. There are some significant changes of use by source (increasing for advertising, personnel and recruitment, new technology and computer servic...

Robert J. Bennett

Papers

SME Growth: The Relationship with Business Advice and External Collaboration

The use of external business advice by SMEs in Britain

The benefits of external support to SMEs: “Hard” versus “soft” outcomes and satisfaction levels

SME Policy Support in Britain since the 1990s: What have We Learnt?:

Changing Use of External Business Advice and Government Supports by SMEs in the 1990s