• Use the 1994 participant database provided by the Defense Nuclear Agency (DNA). (See Appendix E for a detailed description of procedures undertaken to validate the completeness of the participant roster.)
  • Restrict analyses to Navy participants and controls (see Chapter 6).
  • Do not include in participant cohort those individuals who came on duty in the CROSSROADS area of operations after the officially designated period of the operation (see Chapter 6).
  • Exclude from the control cohort those also in the participant cohort (see Chapter 6).
  • Include participants and controls who have other-than-CROSSROADS nuclear test participation (see Chapter 6).
  • Use male mortality rates, since the control cohort is almost totally male (gender generally was not recorded on the research files for participants), when making comparisons to standard populations (e.g., the U.S. population for specific years). However, do not exclude female military personnel from the participant or control study cohorts.
  • Do not use dosimetry; use exposure surrogate variables (see Chapter 8).

Data Cleaning and Variable Development

  • Code vital status outcome as a dichotomy: "Known Dead" and "Not Known to be Dead." The latter included participants and controls known to be alive, having date of death after prearranged study cut-off (31 December 1992), and others for whom no death confirmation was obtained through the Department of Veterans Affairs (VA), who were presumed to be alive (see Chapter 9).
  • For VA claims folders that did not contain a date of death from VA records or an acquired death certificate and that had been transferred from VA to a Federal Archives Record Center (FARC), use date of folder transfer to calculate an estimated date of death (see Chapter 9).
  • Because military records used only two digits to designate year of birth, assign a century-of-birth prefix of "l9" to years of birth 00 to 30 and the prefix "18" to years 31 to 99.
  • Create a "boarder" variable to include participants assigned in the appropriate time period to one or more units known to be a target ship, a radiation safety unit, or a boarding team (see Chapter 8).
  • Consolidate occupational specialty information into a two-level analysis variable (Engineering & Hull enlisted, other enlisted) to capture hypothesized exposure differences (see Chapter 8).
  • Because of small numbers (paygrade and rank) or unavailable information (occupation), consider all officers as one category.

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