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. 2012 Sep 14;12:218. doi: 10.1186/1471-2334-12-218

Table 3.

Smear and culture results for all SE, smear negative and smear positive SE

Description All smears All cultures Cultures in SN SE Cultures in SP SE
Number of SE
 2537
 2537
 2060
 477
Observed # of P SE after 1 specimen
 377
 682
 253
 429
Observed # of P SE after 2 specimens
 477
 733
 301
 432
Proportion of P SE on 1st specimen
 0.149
 0.269
 0.123
 0.899
Proportion of NP SE
 0.060
 0.042
 0.040
 0.103
# of P SE missed by failing to do 2nd specimen
 31
 27
 25
 2
Expected # of P SE after 1 specimen
 377
 682
 253
 429
Expected # of P SE after 2 specimens
 508
 760
 326
 434
Expected proportion of P SE after 1 specimen
 0.149
 0.269
 0.123
 0.899
Expected proportion of P SE after 2 specimens
 0.200
 0.299
 0.158
 0.910
Potential IY for 1st specimen
 0.743
 0.898
 0.776
 0.989
Potential IY for 2nd specimen
 0.257
 0.102
 0.224
 0.011
Overall fraction of P on 1st specimen
 0.149
 0.269
 0.123
 0.899
Overall fraction of P on 2nd specimen
 0.052
 0.031
 0.035
 0.010
NND on 1st specimen
 7
 4
 8
 1
NND on 2nd specimen 19 33 28 96

Legend: S = smear, P = positive, N = negative, SE = Suspect Episodes, NND = number needed to diagnose (see Methods for details), IY = incremental yield.