An Empirical Study of Price Correlations: 2. The Decrease in Price Correlation with Distance and the Concept of Correlation Length
The dependence of the correlation between wheat price fluctuations on different markets with respect to the distance between those markets is investigated. It is shown that the decrease in the correlation is exponential and is governed by a characteristic distance which is called the correlation length for wheat prices. This is a measure of the level of market integration in a given area. The magnitude of the correlation length is compared for different cereals: wheat, rye, and oats, and the evolution of the correlation length during the 19th century is studied. In particular, it is observed that subsistence crises are characterised by a collective behaviour of the economy which results in a sudden peak in the correlation length. Last, the part played by the spatial correlation between precipitations is investigated. It appears to be rather small; consequently, the price-correlation length is primarily the result of economic factors.
Spatial analysis of real estate price bubbles: Paris, 1984–1993
Abstract The Paris housing price bubble that started around 1984 came to a burst in 1990–1991. In order to get insight into the spatial mechanism of speculative bubbles, we examine this episode at the level of the twenty districts composing Paris intra-muros. The analysis is carried out in two steps. First, we empirically describe the price movements in the different districts. Prices in the best areas are seen to peak first and by and large to decrease in proportion to their former increase. Our second objective is to characterize each district in terms of the relative strength of speculative trading versus price–supply inelasticity. We show that the various price trajectories can fairly well be described in the framework of a partial equilibrium model which stylizes the behaviour of the different kinds of agents in the market. The model thus provides a classification of the districts in terms of speculative trading intensiveness versus supply inelasticity.
Investigation of the relative sensitivity of control of impulse X-ray television systems
Method of calculating the relative sensitivity for X-ray television systems based on X-ray screens, CCD cameras and impulse x-ray devices was proposed. To visualize the images formed by the pulsed X-ray radiation, an adjustable duration of accumulation on the CCD camera was used. The relative sensitivity of the control is determined by the intersection of dependences of the luminance and threshold contrast on the size of the defect. The comparison of calculated and experimental values of the relative sensitivity of control is made in this paper.