Reference standards and units allow independent labs to make sharable measurements. Each laboratory followed the same measurement procedure, measuring relative promoter activities based on GFP concentration measured via a flow cytometer. Measurements were taken in triplicate; the boxes show the highest and lowest measured relative promoter activities and the whiskers show the 95% confidence interval of the mean of the activities. The large range in the 95% confidence interval (extending beyond the highest and lowest measured activities) is partially a function of the small number of replicates (three) that were conducted by each laboratory. The activity of BBa_J23113 was equivalent to the negative control within error for all but one of the laboratories. The measured activities of the other three promoters were fairly consistent across laboratories with less than a 2-fold range of activities measured for each promoter across all labs (BBa_J23150: 0.14 – 0.23; BBa_J23150: 0.38 – 0.606; BBa_J23103: 0.77 – 0.96).