I, OTI, Samuel Oji declare that this research report is my own work. It is being submitted for the degree of Master of Science in Medicine in the field of Epidemiology and Biostatistics in the University of Witwatersrand, Johannesburg. It has not been submitted before for any degree or examination at this or any other University. ……………………………. [Signature of candidate] ……………… … day of …………………, 200…