A Bayesian Model for Estimation of Population Proportions

• Activity Number: 186
• Type: Invited
• Date/Time: Monday, August 1, 2011 : 10:30 AM to 12:20 PM
• Sponsor: Section on Bayesian Statistical Science
• Author(s): Raymond Okafor*+ and Ugochukwu Ahamefula Mbata
• Companies: University of Lagos and University of Lagos
• Keywords: Estimation, Empirical Bayes ; Faculties at Main Campus, Proportions using Vehicles ; Sample Surveys, Traffic Congestion ; Undergraduates ; UNILAG ; Use of Motor Vehicles.

Abstract

Traffic congestion and parking difficulties, have become a major concern to members of the University of Lagos (UNILAG). UNILAG has witnessed unprecedented growth in student's enrolment, in the last ten years or so culminating in the current total enrolment of more than thirty-five thousand students, of which about twenty-five thousand are undergraduates. In order to study the worrisome traffic situation, independent, though similar, sample surveys of undergraduates of the eight faculties on the main campus were conducted in 2007. The purpose of the surveys was to collect data on undergraduates who owned or used motor vehicles on campus. Further, to investigate possible temporal trends, the surveys were repeated in 2009. The types of data obtained from the surveys provided avenue for the application of Empirical Bayes (EB) analysis to estimate the proportions of students of individual faculties who used motor vehicles on campus roads during the periods under reference. The EB technique, being a Bayesian method, combines prior information and sample information in a manner that "shrinks" an EB estimator towards the sample estimator if a vague prior is used.