Table 2.

The sensitivity and specificity of the heterozygous sites and Bayesian model-based clustering approaches for detecting mixed infection in artificial mixture and replicate samples. Calculations assume that the 4 technical replicates of one sample that were classified as mixed by the heterozygous sites method came from a pure sample. True positives were taken as the known artificially mixed Malawi samples (Table 1), and true negatives as the known pure Malawi samples (Table 1), and all H37Rv and Portuguese replicate strains (Additional file 1)

	Number of mixed samples detected
	Heterozygous sites method	Bayesian model-based clustering
Artificial mixed Malawi samples	33/36	27/36
Pure Malawi samples	0/12	0/12
Technical replicates	0/18	0/18
Biological replicates	4/32	0/32
Sensitivity of method	91.7%	75.0%
Specificity of method	93.5%	100%