Table 1 Definitions of validity terms

Count accuracy

Number of outlets is neither an under- nor over-count

Classification accuracy

Business type is correctly identified

Locational accuracy

Geographic coordinates are accurate within an acceptable level of precision

True positive (TP)

Outlet present in business list and observed on the ground

False positive (FP)

Outlet present in business list and not observed on the ground

True negative (TN)

Outlet not present in business list and not observed on the ground

False negative (FN)

Outlet not present in business list and observed on the ground

Sensitivity

Proportion of observed outlets that are included in the business list: (TP)/(TP + FN)

Positive predictive value (PPV)

Likelihood that an outlet present in the business list is observed: (TP)/(TP + FP)

Concordance

Proportion of outlets both present in the business list and observed out of all outlets either in the business list or observed: (TP)/(TP + FP + FN)