Figure 1From: Intervene before leaving: clustered lot quality assurance sampling to monitor vaccination coverage at health district level before the end of a yellow fever and measles vaccination campaign in Sierra Leone in 2009 Operating characteristic curve for LQAS rule rejecting programmes with more than 7 defectives in a sample of 50 assuming simple random sampling (no clustering). Two vertical lines are placed at the lower and upper thresholds.Back to article page