Migration,rank-size distribution,and economic development: The case of Mexico

This is an examination of whether city size is truly an independent variable when the relationships between city size and certain economic and social phenomena are considered. A new hypothesis is presented that postulates that relative or systemic city size is an independent variable that affects urban growth patterns through varying, non-optimum migration flows. The hypothesis is tested using official Mexican data for the period 1960 to 1970.     

Evaluating a new computer-based system for face recall

The Computer-Aided Design Centre has developed a new face recall system which enables a witness to construct the image of a suspect on a television screen. The system currently uses the Photofit library and method of construction. Likenesses of target faces produced by subjects (n=36) using the new system were compared to conventional Photofits produced by a second group of subjects (n=36) of the same targets. There was no difference on any of the three measures employed in the assessed quality of the likenesses produced by Photofit and the CADC System. Both systems tended to produce more recognizable composites when construction was carried out in the presence of the target compared to its absence. Composites made from memory on the initial trial were marginally better with the CADC System than with Photofit. While both systems showed low absolute accuracy, they enjoyed a measure of success in transmitting a likeness of a facial type. It is concluded that while the CADC system shows promise, psychological constraints upon witnesses' powers of recall may place limits on the absolute accuracy achievable with any system of face reconstruction.These experiments were financed by grant No. POL/73 1675/24/3 from the Police Scientific Development Branch of the U.K. Home Office. Points of view expressed in this article are solely those of the authors and do not necessarily reflect the opinions or positions of the funding body. Our gratitude and thanks are due to Tony Kitson and Clive Holloway for their many hours spent developing and operating the CADC system; Jean Shepherd for her skills as a Photofit operator; the Computer-Aided Design Centre; and the MRC Applied Psychology Unit, Cambridge for facilities and subjects.