Reducing under-reporting of stigmatized health  events using the List Experiment: results from  a randomized, population-based study of  abortion in Liberia.
BACKGROUND
Direct measurement of sensitive health events is often limited by high levels of under-reporting due to stigma and concerns about privacy. Abortion in particular is notoriously difficult to measure. This study implements a novel method to estimate the cumulative lifetime incidence of induced abortion in Liberia.


METHODS
In a randomly selected sample of 3219 women ages 15–49 years in June 2013 in Liberia, we implemented the ‘Double List Experiment’. To measure abortion incidence, each woman was read two lists: (A) a list of non-sensitive items and (B) a list of correlated non-sensitive items with abortion added. The sensitive item, abortion, was randomly added to either List A or List B for each respondent. The respondent reported a simple count of the options on each list that she had experienced, without indicating which options. Difference in means calculations between the average counts for each list were then averaged to provide an estimate of the population proportion that has had an abortion.


RESULTS
The list experiment estimates that 32% [95% confidence interval (CI): 0.29-0.34) of respondents surveyed had ever had an abortion (26% of women in urban areas, and 36% of women in rural areas, P-value for difference < 0.001), with a 95% response rate.


CONCLUSIONS
The list experiment generated an estimate five times greater than the only previous representative estimate of abortion in Liberia, indicating the potential utility of this method to reduce under-reporting in the measurement of abortion. The method could be widely applied to measure other stigmatized health topics, including sexual behaviours, sexual assault or domestic violence.
Department of Epidemiology & Biostatistics, University of California, San Francisco, CA, USA. heidi.moseson@ucsf.edu
Heidi
H
Moseson
Moses
M
Massaquoi
Christine
C
Dehlendorf
Luke
L
Bawo
Bernice
B
Dahn
Yah
Y
Zolia
Eric
E
Vittinghoff
Robert A
RA
Hiatt
Caitlin
C
Gerdts
D000028:Abortion, Induced / Q000706:statistics & numerical data*; D000293:Adolescent; D000328:Adult; D003625:Data Collection / Q000379:methods*; D005260:Female; D006306:Health Surveys; D006801:Humans; D007988:Liberia; D016014:Linear Models; D008875:Middle Aged; D011247:Pregnancy; D018907:Privacy; D057566:Self Report; D012725:Sexual Behavior; D057545:Social Stigma; D013240:Stereotyping; D011795:Surveys and Questionnaires; D055815:Young Adult