Political fragmentation,competition, and investment decisions: the medieval grinding industry in Ponthieu,France, 1150–1250

This article explores the effects of political structure on rulers' monopolistic gains and investment decisions in the context of the medieval milling industry in northern France, 1150–1250. Using Salop's spatial model, this article aims to show that political fragmentation increased investment in watermill construction because it reduced the capacity of rulers to limit competition from neighbouring mills. The calculations demonstrate that competition significantly reduced rulers' income from watermills and that the construction of more than 50 per cent of these mills cannot be economically ‘justified’ unless rulers' profit maximization over joint production is considered, and revenues from additional labour allocated to wheat production is included.     

Textile characteristics,laundering and the environment

The environmental impact of laundering is dependent on the laundry methods used by households. This study investigates the relation between laundry methods (frequency, load size and wash temperature) and the composition of wash loads. Three definitions for the composition of wash loads are used: the respondent's classification and two objective definitions. These are constructed in two different ways from three specific characteristics of the textiles: colour, textile fibre and the type of article. The data are from a survey with a 2-week diary about laundry practices of 1026 Dutch households in 1990. The results show that all three definitions of the composition of wash loads can explain one factor of the laundry method, wash temperature; frequency and load size, however, are not influenced by the composition of the wash load.     

Towards an analysis of tax effects on labour market and allocation: A micro/macro approach

Summary Tax effects on labour market and allocation are analysed with a sectoral model which is based on the microeconomic theory of the behaviour of economic agents. The model contains a highly disaggregated household sector, an enterprise sector, equilibrium unemployment on the labour market and a detailed modelling of institutional aspects of the tax and social security system. The model is calibrated for 1985. Simulation results show that temporary increases of world trade and higher value-added tax rates do not affect the equilibrium unemployment rate in the long run. A higher replacement rate of unemployment benefits increases unemployment and a tax reform containing lower marginal and average tax rates reduces unemployment.The authors thank F.J.H. Don, C.J.J. Eijgenraam, F.H. Huizinga and R.M. van Opstal for assistance on the household model, the cumulated production structure approach, the wage model and the model of firm behaviour respectively, and other colleagues of the Central Planning Bureau for useful comments.See Shoven and Whalley (1984) and Borges (1986) for reviews, and Keller (1980) for an application to The Netherlands.See, for instance, Abel (1980), Summers (1981), Bruno and Sachs (1985), Van de Klundert and Peters (1986).Ginsburgh and Mercenier (1988) review AGE modelling and the disequilibrium approach.