TABLE 2.

Negative predictive values for self‐reported methamphetamine use using three methods

	NPV (%)	(95% CI)
Primary analysis (original values)
Naive method (ignoring within‐person clustering)	82.7	76.5–87.9
Logistic regression (adjusting the SE for clustering)	82.7	73.9–91.5
GEE (exchangeable correlation matrix)	76.8	73.9–91.5
Sensitivity analysis (imputed values)
Naive method (ignoring within‐person clustering)	82.4	76.7–88.0
Logistic regression (adjusting the SE for clustering)	82.4	75.0–89.7
GEE (exchangeable correlation matrix)	79.3	70.9–87.7

GEE = general estimating equation; NPV = negative predictive value; SE = standard error; CI = confidence interval.