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Table 2 Sample sets used for the examination of Kato-Katz and qPCR technical variability

From: Sources of variability in the measurement of Ascaris lumbricoides infection intensity by Kato-Katz and qPCR

Sample Questions addressed
34 Kato-Katz slides containing Ascaris lumbricoides eggs, each read by five technicians. These 34 slides are a subset of 50 slides read by five technicians (other than the 34, these slides did not contain A. lumbricoides eggs). To assess reader-to-reader differences in measurement.
16 of the 34 slides have corresponding qPCR results (note: only readings by the first four readers are included in this sample, to make it comparable to qPCR samples read in quadruplicate). To compare variability in measurements from the same sample between qPCR and Kato-Katz.
351 slides from 158 individuals at baseline, each read by one of nine readers. Two thirds were from the first stool collected from each individual, and the remainder were from the second stool. Twenty percent (72/351) of these slides were judged to be poorly made, based on being poorly spread or totally opaque. Twenty-three percent (82/351) of slides were from people who later expelled a worm following treatment. To assess the relative contribution of different factors (listed in Additional file 1: Table S1) to the variability in egg intensity measurements by Kato-Katz.
Four qPCR quantity measurements from each of 284 samples that were tested by qPCR and had at least one positive reading for A. lumbricoides. Additional information about deviation of individual measurements from the mean measurement, to supplement the data from the four stool samples discussed directly below.
Four de-identified stool samples, split into 11 pieces each. Each stool sample was extracted after being split into 11 different pieces, and each of these 11 samples was run in four wells on each of three plates. These four people are not associated with a number of worms expelled. To assess the relative contribution of different factors (listed in Additional file 1: Table S1) to the variability in egg intensity measurements by qPCR.
383 A. lumbricoides worms expelled at baseline and 141 expelled at follow-up. Examine the reliability of worm expulsion by calculating its sensitivity, and explore whether the sizes of worms expelled at follow-up suggest that egg excretion might have been suppressed following baseline treatment.