BSNUM is a two-digit count variable.
00: Not in Universe
21: Top code of 21 or more
98: Unknown-Not Ascertained
99: Unknown-Don't Know
For sample adults, BSNUM reports the number of biological sons (either alive or dead) of the respondent. Although this information was collected and used to determine if respondents were asked follow up questions in each cancer module, the number of biological sons was suppressed on the public use file beginning in 2015.
The Manuals for all three years define "biological" relatives as people related by blood. Thus, a respondent's biological son is a son related to the respondent by blood (i.e., not a stepson, adopted son, foster son, or son-in-law).
BSNUM is one of a series of related variables in the "Family History" section of the 2000, 2005, and 2010 Cancer Modules. In all three years, 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 biological sons, see the variable description for BSBLCAN, which reports whether the respondent had at least one biological son who ever had bladder cancer.
In addition to questions about biological son(s), the "Family History" section of the 2000, 2005, and 2010 Cancer Modules also included questions about respondents' biological daughter(s), full brother(s) (i.e., brother(s) with the same biological father and biological mother as the respondent), and full sister(s). For each, there is a variable reporting the number of such persons:
- (BDNUM) reports the number of biological sons
- (FBNUM) reports the number of full brothers
- (FSNUM) reports the number of full sisters
BSNUM is fully comparable between 2005 and 2010.
BSNUM is largely comparable between 2000 and 2005/2010, though there may be some difference in the meaning of "refused," "not ascertained," and "don't know" as used in 2000 compared to the meanings of those terms in 2005 and 2010.
The Survey Descriptions for all three years caution that while "all sample adults were to be asked the questions in the Cancer Control Module, some persons did not complete the supplement." However, whereas 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, in 2005 , 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: Sample adults age 18+.
- 1987, 2000, 2005, 2010
- 1987, 2000, 2005, 2010 : SAMPWEIGHT