FBNUM is a two-digit count variable.
03: Beginning in 2015, top code of 3 or more
21: Prior to 2015, top code of 21 or more
96: Not in Universe
98: Unknown-Not Ascertained
99: Unknown-Don't Know
For sample adults, FBNUM reports the number of full brothers (either alive or dead) of the respondent.
The Manuals define "full siblings" as people who have "the same biological father and mother." Thus, a respondent's full brother is a brother who has the same biological father and mother as the respondent (i.e., not half-brothers, stepbrothers, adopted brothers, foster brothers, or brothers-in-law).
FBNUM is one of a series of related variables in the "Family History" section of the Cancer Module. This section begins with the general comment:
According to the 2000 and 2005 Field Representative's Manuals, the purpose of this and other family cancer history questions is to "determine the prevalence of cancer in families in the population" to "allow a greater understanding of how data obtained from genetics clinics can be applied to the general population." The 2010 Manual provides a similar rationale, stating that the collection of this data "will allow analysts a greater understanding of how family history relates to cancer. For a full list of available cancer family history variables relating to full brothers, see the variable description for FBBLCAN, which reports whether the respondent had at least one full brother who ever had bladder cancer.
In addition to questions about full brother(s), the "Family History" section of the Cancer Module also included questions about respondents' biological daughter(s), biological son(s), and full sister(s) (i.e., sister(s) with the same biological father and biological mother as the respondent). For each, there is a variable reporting the number of such persons:
- (BDNUM) reports the number of biological sons
- (BSNUM) reports the number of full brothers
- (FSNUM) reports the number of full sisters
Although FBNUM is substantively comparable across all years, users should note two changes in the recoding of values that may affect analyses of data from multiple cancer supplement years.
The first, and most recent, change affects the top code value for FBNUM. Prior to 2015, FBNUM was top coded at 21. Starting in 2015, FBNUM was top coded at 3. The second change, affecting how missing data values were treated for sample adults who completed only part of the cancer supplement, took place between the 2000 and 2005 cancer supplement. In 2000, persons who answered less than 50 percent of the questions in the supplement had a value of "not ascertained" automatically inserted in the appropriate fields of the Cancer Control Module file, whereas in 2005 and later years, persons who answered none of the questions in the supplement had a value of "not ascertained" automatically inserted in the appropriate fields of the Cancer Control Module file.
- 1987: Half of sample persons age 18+ (excluded from CACT).
- 2000; 2005; 2010; 2015: Sample adults age 18+.
- 1987, 2000, 2005, 2010, 2015
- 1987, 2000, 2005, 2010, 2015 : SAMPWEIGHT