Table 3.

Tier 2—proportions of responses missing when asked about contraceptive start and stop month or year of interviewer-administered (IA) and self-administered (SELF) among 19 female respondents with cystic fibrosis (only 2 most commonly used birth control methods shown).

Contraceptive		Year of use	Month of use
Condoms (n=17)a
	SELF	23.9% (11/46)	63.3% (19/30)
	IA	22.2% (10/45)	16.7% (5/30)
Birth control pills (n=16)a
	SELF	39.2% (20/51)	53.6% (15/28)
	IA	2.0% (1/51)	3.6% (1/28)

^aRaw numbers do not add up because some women used methods multiple times over a period of 12 years.