Term | Definition | Example |

Statistic | Summary of sample and estimation of unknown population parameter | NPV is estimated from sample |

Parameter | Number summarizing population | NPV is determined for test in population |

H_{0} | Specific statement about parameters of population | H_{0} is NPV_{PET/CT} of less than 90% |

H_{A} | Broad statement that pairs with, yet is mutually exclusive from, H_{0} | H_{A} is NPV_{PET/CT} of at least 90% |

Test statistic | Summary of information from sample | When comparing 2 means assuming normal distribution, with z as test statistic, z follows standard normal distribution |

P value | Probability of obtaining sample statistic at least as extreme as test statistic in direction of H_{A} if H_{0} were true | z of 2.26 (calculated from comparing 154 patients with observed FNR of 15% to 154 patients with observed FNR of 7%) corresponds to P value of 0.0238 |

Type I error (α) | Probability of rejecting H_{0} when true | Phase 3 superiority trials are commonly designed with 1-sided type I error of 0.025 |

Type II error (β) | Probability of failing to reject H_{0} when false (i.e., H_{A} holds) | When clinical trials are designed, type II error is set priori, with β of 0.05–0.20 commonly used |

Statistical power (1 − β) | Probability of rejecting H_{0} when H_{A} is true | Clinical trials are commonly designed with 80%–95% power |

CI | Range of possible values of true parameter based on specified level of confidence | Pathologic analysis of SLNs by routine hematoxylin and eosin revealed NPV of 0.94, with 95% CI of 0.88–0.98 (26). |

Familywise error rate control | Control of probability of at least one type I error | Bonferroni adjustment divides type I error by number of tests |

False-discovery rate control | Control of proportion of significant results that are actually false-positives | Hochberg step-down procedure orders P values to compare with adjusted α |

NPV = negative predictive value; NaF PET/CT = sodium fluoride positron emission tomography.