From: High yield of culture-based diagnosis in a TB-endemic setting

Description | Formula | |
---|---|---|

Ad | Number of SE who had specimens examined | Px + NP + NN + N9 |

Observed # of P SE after 1 specimen | Px | |

Od | Observed # of P SE after 2 specimens | Px + NP |

Sd1 |
Fraction of SE found positive on the 1^{st} specimen
| Px/(Px + NP + NN + N9) |

Sd2 | Fraction of SE found to be negative on the 1st specimen but positive on the 2nd | NP/(NP + NN + N9) |

Md | # of P SE missed by failing to do a 2nd specimen | Sd2 * N9 |

Expected # of P SE after 1 specimen: same as Observed # of P SE after 1 specimen | ||

Ed | Expected # of P SE after 2 specimens (if all suspects had 2 specimens done) | Od + Md |

Expected proportion of P SE after 1 specimen: same as Sd1 | ||

Rd | Expected proportion of P SE after 2 specimens | Ed/Ad |

Fd1 |
Fraction for the potential IY from the 1^{st} specimen
| Px / Ed |

Fd2 |
Fraction for the potential IY from the 2^{nd} specimen
| (Md + NPx) / Ed |

OFP1 |
Overall fraction of P on 1^{st} specimen
| Rd * Fd1 |

OFP2 |
Overall fraction of P on 2^{nd} specimen
| Rd * Fd2 |

NND1 | NND on 1st specimen: number of specimens needed to be examined to find one additional case | 1/OFP1 |

NND2 | NND on 2nd specimen | 1/OFP2 |