National Health and Nutrition Examination Survey

The ACASI section on sexual behavior (SXQ) provides information on lifetime and current sexual behavior for both men and women. Major items in this section include age at first sexual intercourse, number of sexual partners, sexual orientation, circumcision status (men) and history of sexually transmitted diseases.

Survey participants aged 14-69 years were eligible. Several questions in this section are age and gender-specific. Mentally impaired individuals or participants who were unable to understand English, Spanish, Korean, Vietnamese, or Chinese (traditional/mandarin, simplified/mandarin, and traditional/Cantonese) were not asked these questions. Only data from participants aged 18-69 years are included in this release. Special use data files for participants 14-17 years are available through the NCHS Research Data Center.

The sexual behavior questionnaire was self-administered in a private room at the examination center, using the Audio Computer Assisted Self Interview (ACASI) system. The ACASI was conducted in one of the following languages: English, Spanish, Korean, Vietnamese, or Chinese (traditional/mandarin, simplified/mandarin, and traditional/Cantonese). The ACASI enables respondents to hear questions through earphones as well as read questions on the computer screen. Respondents move at their own speed and touch the screen to indicate their response. No proxy respondents or translators were used in situations when the respondents could not self-report. The questionnaire is located on the NHANES website at: https://wwwn.cdc.gov/nchs/data/nhanes/2011-2012/questionnaires/sxq_acasi.pdf

For details on the QA/QC process for this component, please refer to the MEC Interview Manual on the NHANES website.

The sexual behavior 2011-2012 questionnaire are the same as the 2009-2010 cycle. However, analyst should be cautious when combining data with cycles prior to the NHANES 2009-2010 SXQ data, since some questions have been removed, questions have been added, and some questions have had slight wording changes. Please see Appendix 1 (for male) and Appendix 2 (for female) for detailed information on variables included in the SXQ section in the latest five release cycles.

The variable SXD021 (Ever had vaginal, anal, or oral sex) was derived from whether or not the respondent had reported having any of the specific types of sex. For example, if a male answered “yes” to having had any of the following types of sex: SXQ800 (Ever had vaginal sex with a woman), SXQ803 (Ever performed oral sex on a woman), SXQ806 (Ever had anal sex with a woman), or SXQ809 (Ever had any sex with a man; anal, oral); he would be coded as a “1” or “yes” in SXD021.

Responses to SXD031 (age at first sexual intercourse), SXD633 (age first performed oral sex on a woman), and SXD621 (age when first had oral sex) that were 9 years or less were grouped and coded as “9 years or younger.”

Information was collected using two-part (number and unit) questions for both SXD630 (last performed oral sex on a new male partner) and SXD642 (last performed oral sex on a new female partner). This is to allow participants to report how long ago they had performed oral sex either in days, weeks, months, or years. The released variables were edited to standardize the reported length of time to number of days, using the following conversion factors: 7 days per week, 30.4 days per month, and 365.25 days per year.

In general, if a person wasn't asked a question, the response to the question is shown as “missing.” It is up to the analysts to recode the response to zero as they see fit. For example, if a respondent reported that they had zero lifetime vaginal sex partners, they wouldn't be asked the number of vaginal sex partners in the past 12 months. Since the respondent does not receive the question about partners in the past 12 months, the data will be coded as missing for this variable. Analysts may want to recode this to “0.”

For questions that ascertain total number of partners for all types of sex (i.e., SXD171, SXD510, SXD101 and SXD450), if the respondent had reported never having any type of sex, the responses were coded as “0.”

Analyst should keep in mind that respondents aged 60-69 years get asked only some questions. It is important to refer to the codebook to see the target age for each question.

Although the ACASI has many advantages over interviewer-administered questionnaires for sensitive information, inconsistent responses can occur. Since the questionnaire is self-administered, unlikely answers or confusing questions cannot be clarified by the interviewer. Although, the questionnaire was programmed to alert respondents of potential data entry errors or inconsistencies, not every possible consistency check was added. To minimize potential respondent frustration and confusion, the interview was not interrupted each time an inconsistent answer occurred in terms of the number of sexual partners for different periods of recall for different types of sexual behavior.

Users are cautioned about the use of SXQ292 and SXQ294 in analyses, especially in analyses that classify respondents by their responses to these questions to describe or compare subgroup characteristics. The sample size for the non-heterosexual subgroups is limited and do not meet the minimum sample size requirements for statistical reliability as noted in the NHANES analytic guidelines. Even after combining multiple years of data, which is often recommended to estimate rarer conditions within a subgroup, the non-heterosexual subgroups do not meet the minimum sample size. Additionally, there is a high rate of not selecting a specific answer to the questions. That is, selecting ‘don’t know’, ‘refused’, ‘not sure’ or ‘something else’ as a response. This issue has been examined at length at the NCHS Questionnaire Design Research Laboratory (QDRL) recently. Individuals select these answers for a variety of reasons that are well summarized in the report Design, Development and Testing of the NHIS Sexual Identity Question1, specifically in Table 2. For example, respondents from the LGBT community select “something else” when they use a different sexual identity label than those presented in the response options. However, those who aren’t part of the LGBT community select this answer because they are not familiar with what the response options mean.

Analysts should be aware that the 2011-2012 sexual behavior data has some inconsistencies in terms of number of partners reported for each type of sex. For example, about 7% of males and 4% of females reported a greater number of vaginal sex partners in the past 12 months compared with number of “total” sex partners in the past 12 months.

Exam sample weights should be used for analyses. Please refer to the NHANES Analytic Guidelines and the on-line NHANES Tutorial for further details on the use of sample weights and other analytic issues.

Special use data files for participants 14-17 years is available through the NCHS Research Data Center (RDC).