Economics Insights @ CBS

This paper describes efforts to validate a multiple car dispatch queueing (MCD) model of police patrol operations using New York City data. The MCD model was designed for use in a computer system that has been disseminated to many police departments in the U.S. to help planners allocate patrol cars among precincts. It has also been used to evalute specific changes in patrol policy in New York. We define validation as a series of hierarchical procedures ranging from tests of mathematical correctness to evaluations of model robustness.

In this paper we show that information in prices that leads (future) earnings is contained in financial statements. While accrual accounting rules produce an earnings number which reflects the information in stock prices with a lag, they also produce a large array of additional numbers presented in the income statement, balance sheet, and statement of changes in financial position. We demonstrate that certain of these numbers can be summarized into one measure that predicts future earnings.

Patterns of optical flow produced at the eye of a moving observer are important for the guidance of locomotion. This study examined age-related changes in the ability to perceive one's direction of self-motion, or heading, from optical flow, using computer displays that simulate translational or curvilinear movement parallel to a random-dot ground surface.