2.2. Sampling and population
A stratified simple random selection method was used to choose eligible nurses from the different wards/units of the identified two referral hospitals. The hospital wards were numbered from 1 to N based on a ward/unit duty roster list of all registered nurses from the Head of Department nursing office in each of the two referral hospitals. Each stratum (ward/unit) was allocated a computer-generated random number, with the size according to the staff makeup. Inclusion criteria included being a registered nurse with the Nigerian Nursing Council, and have given their written consent, being able to read and write in English and are currently working in the following wards/unit; male and female medical, and surgical wards, as well as intensive care unit (ICU), accident and emergency (A&E) and general outpatient department (GOPD). The exclusion criteria included those that were be trained in CPR in the last 3 months before the start of this study.The sample size was computed using two mean formula (