Codes and Frequencies
For sample adults who had taken any vitamin C in the past 12 months (VITAMINC), VITAMINCMO reports the number of months that respondents had taken vitamin C. The survey question did not require that the months be consecutive.
VITAMINCMO is one of a series of variables reporting how often and over what period of time respondents had taken vitamin C. For VITAMINCMO, interviewers asked respondents directly about the number of months in the past 12 they had taken vitamin C.
In 2000 only, for months during which they had taken vitamin C, respondents reported how often they had taken this nutrient (VITAMINCNO), answering as they desired in terms of days per week or days per month (VITAMINCTP).
The National Center for Health Statistics recoded data from VITAMINCNO and VITAMINCTP to create two new variables with consistent time units: Number of days per week took vitamin C during the relevant months of the past 12 months (VITAMINCDWK), and number of days per month took vitamin C during the relevant months of the past 12 months (VITAMINCDMO). VITAMINCDMO is also available for 1987 and 1992, when it was asked as a direct question.
Variables similar to VITAMINCMO are available for the following vitamin/mineral supplements (with years indicating availability):
- Beta carotene (VITABETAMO, 2005)
- Calcium (VITACALCMO, 1987, 1992, 2000, 2005)
- Vitamin A (VITAMINAMO, 1987, 1992, 2000)
- Vitamin E (VITAMINEMO, 1987, 1992, 2000, 2005)
- Multi-vitamins (VITAMULTVMO, 1987, 1992, 2000, 2005)
- Selenium (VITASELNMO, 2005)
For more information on the full range of variables related to vitamins, see VITANY.
VITAMINCMO is largely comparable across all years. Apart from the differences in universe, there is a slight change in the categories over time.
In 1987, interviewers could record responses of "less than one month" as a separate category from "1 month". However, in 1992 and 2000, the smallest time unit available is 1 month. Thus, to maximize comparability, researchers should treat "less than one month" and "1 month" as one category across years, because in 1992 and 2000, "1 month" includes responses that would have been coded "less than one month" if such a category had been available in those years.
- 1987: Half of sample persons age 18+ (excluded from CACT supplement) who took vitamin/mineral supplements and took vitamin C in the past 12 months.
- 1992: Half of sample persons age 18+ in quarters 1 and 2, and in 2 weeks of quarter 3 (excluded from CACT supplement) who took vitamin C in past 12 months.
- 2000: Sample adults age 18+ who took vitamin C in past 12 months.
- 1987, 1992, 2000
- 1987, 1992, 2000 : SAMPWEIGHT