Sample size {14}
HAI infection, FM
The participant timeline is shown in Fig. Timeline for enrolment, interventions and assessments of the study. FM fluorescent markers, HAI healthcare-associated infectionThe study design ensures a sample size sufficient to detect a relative reduction of at least 35% in total HAI infection, with a baseline point prevalence of 11%. It is powered at 80%, based on a two-sided 5% significance level with an inter-cluster correlation of 0.3 and coefficient of variation of 0.65—allowing for variation in cluster size. A stepped wedge sample size formula was used, considering the number and size of clusters and the time period. The required cluster size is 132 (66 per ward), achieved with two wards forming clusters and three fortnightly PPS each time period (