Study population, sample and sampling method
The study involved health professionals who worked as CPs. Due to the security and
safety issues due to conflict and Covid-19 pandemic, the study was only conducted in Aden. It has a total population of 987,904, where 550,602 people live in the city of Aden (https://populationstat.com/yemen/aden). The target respondent was CPs in-charge of a pharmacy, and the respondent was excluded if he/she showed lack of willingness to participate in the study or was on leave during the study. The study participant selection and sampling method are described below. A total of 450 CPs took part in our research. The following sampling formula was used:
where n= sample size, Z= Z statistic for a given level of confidence; at 95%, the conventional value is 1.96. P= expected prevalence or proportion (in decimal representation; e.g., for 50% prevalence, P= 0.5), and d=precision (in decimal representation; e.g., for 5% precision, d=0.05). Assuming a dropout rate of 30%, final n=450.
Convenience sampling was conducted to choose the respondents due to the difficulty of having a sampling frame. All of them resided in Aden city. Respondents with different education levels were selected for this study.