你可以算概率。 ART 测试本来的 假阴性 概率可能是 42%。 (1-58%)
"In people with confirmed COVID-19, antigen tests correctly identified COVID-19 infection in an average of 72% of people with symptoms, compared to 58% of people without symptoms. " https://www.cochrane.org/CD013705/INFECTN_how-accurate-are-rapid-tests-diagnosing-covid-19
再加上 conditional probability adjustment. condition 是, 家里有女佣 ART positive, 家里弟弟(或妹妹)已经有发烧症状。 求这个 哥哥 (或姐姐) 已经被感染,但是 ART 显示阴性 是 假阴性 的 概率。