When comparing institutional to municipal sites, there was a distinct difference seen in single-marker frequency (Table 2). In institutional sites, the best single target was N2, which was present in 84% of samples (Table 2). In municipal sites, the best single target was N1, which was present in 93% of samples (Table 2). When looking at dual marker frequency in institutions versus municipalities, N1/N2 was the best combination for both groups (97 vs. 98% respectively, Table 2). It is also interesting to note that in municipal sites, N1/E was a close second showing up in 97% of samples (Table 2). Finally, when looking at samples below the MDL, institutional sites had a much higher percentage of sites below the MDL (39%) when compared to their municipal counterparts (12%) (Table 2).
Frequency of positive samples in municipal and institutional sites* as well as the percent of samples below the minimum detection limit (MDL)
| Site type (n) . | N1 . | N2 . | E . | N1 or N2 . | N1 or E . | N2 or E . | < MDL . |
|---|---|---|---|---|---|---|---|
| Municipal (509) | 93% (90–95) | 86% (83–89) | 75% (71–79) | 98% (96–99) | 97% (95–98) | 91% (88–94) | 12% |
| Institutional (942) | 79% (75–82) | 84% (81–87) | 55% (51–59) | 97% (95–98) | 83% (80–86) | 89% (87–92) | 39% |
| Site type (n) . | N1 . | N2 . | E . | N1 or N2 . | N1 or E . | N2 or E . | < MDL . |
|---|---|---|---|---|---|---|---|
| Municipal (509) | 93% (90–95) | 86% (83–89) | 75% (71–79) | 98% (96–99) | 97% (95–98) | 91% (88–94) | 12% |
| Institutional (942) | 79% (75–82) | 84% (81–87) | 55% (51–59) | 97% (95–98) | 83% (80–86) | 89% (87–92) | 39% |
*95% confidence intervals are shown in parentheses.