Table 1.

Characteristics of the two studies and results of their analysis

First author of study	Drakeley[29]	Ngasala[30]
Objective of study	evaluation of associations between parasite prevalence, altitude and rainfall	evaluation of training in clinical and microscopical diagnosis
Location	two regions of north-eastern Tanzania	two coastal districts north of Dar es Salaam Tanzania,
Study design	population based cross-sectional surveys along altitude transects in those aged up to 45 years	cluster-randomized trial with slides taken from febrile children aged under five years presenting to primary health care (PHC) facilities
Total number of paired readings in dataset	1,601	973
Number of double-zero pairs excluded	37	345
Number of pairs excluded due to missing readings	0	39
Number of pairs excluded due to semi-quantitative readings	0	61
Numbers of paired readings analysed	1,564	528
Mean difference in square root counts (95% confidence interval, p value)	(not done because the dataset did not identify individual readers)	-1.51 (-2.1 to -0.95, p < 0.0001), with central laboratory tending to read higher than PHC
95% limits of agreement in terms of square root counts, i.e. 2.5 and 97.5 percentiles (ideal limits are -1.39 to +1.39)	-5.3 to +4.7	15.2 to +9.2
95% limits of agreements in parasites/μl at average density of 2,000 parasites/μl (ideal limits are ± 780 parasites/μl)	-2,800 to +2,500	8,600 to +5,200/μl
95% limits of agreements in terms of parasites/μl at average density of 10,000 parasites/μl (ideal limits are ± 1,800)	-6,200 to +5,700	-19,200 to +11,700