Table 1.

Sample size determination using two population proportion formulas from significantly associated factors.

Variables	CI	Exposed to unexposed ratio	Power	% of outcome in un-exposed	OR	Sample size including 10 % NRR
Know free of charge gov't ambulance service (Yes/No) [27]	95	1:1	80	37.67 %	2.8	152
Intention to call if it was a toll-free three-digit number (Yes/No) [27]	95	1:1	80	34.52 %	2.6	176
Prior use of Ambulance (Yes/No) [28]	95	1:1	80	28.44 %	4.1	88