Examination of the demographic representativeness of a cross-sectional mobile phone survey in collecting health data in Colombia using random digit dialling

Objectives As mobile phone ownership becomes more widespread in low-income and middle-income countries, mobile phone surveys (MPSs) present an opportunity to collect data on health more cost-effectively. However, selectivity and coverage biases in MPS are concerns, and there is limited information about the population-level representativeness of these surveys compared with household surveys. This study aims at comparing the sociodemographic characteristics of the respondents of an MPS on non-communicable disease risk factors to a household survey in Colombia.Design Cross-sectional study. We used a random digit dialling method to select the samples for calling mobile phone numbers. The survey was conducted using two modalities: computer-assisted telephone interviews (CATIs) and interactive voice response (IVR). The participants were assigned randomly to one of the survey modalities based on a targeted sampling quota stratified by age and sex. The Quality-of-Life Survey (ECV), a nationally representative survey conducted in the same year of the MPS, was used as a reference to compare the sample distributions by sociodemographic characteristics of the MPS data. Univariate and bivariate analyses were performed to evaluate the population representativeness between the ECV and the MPSs.Setting The study was conducted in Colombia in 2021.Participants Population at least 18 years old with a mobile phone.Results We completed 1926 and 2983 interviews for CATI and IVR, respectively. We found that the MPS data have a similar (within 10% points) age–sex data distribution compared with the ECV dataset for some subpopulations, mainly for young populations, people with none/primary and secondary education levels, and people who live in urban and rural areas.Conclusions This study shows that MPS could collect similar data to household surveys in terms of age, sex, high school education level and geographical area for some population categories. Strategies are needed to improve representativeness of the under-represented groups.