The TLMS is based on specific survey months of the Tobacco Use Supplement to the Current Population Survey, and selected cohorts from the National Longitudinal Mortality Study. These are one-time data collection processes with no subsequent data collection follow up. Therefore, one limitation of TLMS data is that they provide a one-time only, baseline, measurement of subjects in a long-term follow-up situation. Another limitation of these data is that, although the survey instruments do provide extensive data collection capabilities in specific subject matter areas, desirable general or specific health information is not collected.  Mortality outcome information is collected from the National Death Index.

Because the Tobacco Use supplements are collected over time, changes in the definitions of variables collected requires harmonization of variables to combine cohorts for analysis purposes.  The harmonization of variables was developed through a collaboration between the Federal Drug Administration (FDA), National Cancer Institute (NCI), and the U.S. Census Bureau.  Harmonization is a complex process because interest in tobacco use and therefore the questions on the surveys have evolved over decades.

The assurance of confidentiality of Census Bureau data is provided by Title 13 of the United States Code (U.S.C.). As such, TLMS operational procedures carefully follow the well-defined practices designed to maintain the confidentiality of personal records as required by Title 13. These practices include the prevention of disclosure through the elimination of sparse cells in publications, the prohibited release of small-area geographical information on the TLMS public-use files, the use of an individually assigned TLMS control number to identify records instead of the use of personal identifiers for these purposes, and the restriction of persons having direct access to the TLMS database. A violation of Title 13 restrictions includes loss of job and assessment of severe penalties including a prison term of up to 5 years and/or fines of up to $500,000, for any individual found guilty of releasing confidential information. In addition, any data acquired from an external agency for TLMS purposes is acquired under the same strict confidentiality protections and practices of Title 13.