A Validation Method to Determine Missing Years of Birth in a Cohort Study of Shipyard Workers Using Social Security Number.

Abstract

The objective of the study is to evaluate the generalizability and feasibility of a prediction method developed by Block et al (1983) to estimate missing age of workers by using their Social Security Numbers (SSNs). Our study used a retrospective occupational cohort of about 15,000 workers from the Long Beach Naval Shipyard (1978 to 1985). Our results showed an 89.2% agreement (P < 0.0001) between the predicted and observed years of birth using Block's method. The correlation increased to 93.1% (P < 0.0001) after our modifications by removing workers with SSNs issued in U.S. territories. The method performed better in shipyard workers who obtained their SSNs after 1950. Although the method is useful in imputing missing age, the accuracy is dependent on the year, age, and location of SSN issuance.