舊文搬家：考題：敏感性&特異性的運用

26歲男性出現失智相關的症狀，囧rz醫師依據病史懷疑他可能得了「當兵腦殘症候群」(MAD：Military Associated Dementia)此疾病經評估大腦功能後可分成二種結果，每個結果有各自的敏感性&特異性：

結果一：病人左腦完全失去正常(patient's left hemisphere had nothing right) 敏感性85%，特異性40%
結果二：病人右腦異常消失(patient's right hemisphere had nothing left) 敏感性45%，特異性90%

在此假設此疾病對左腦和右腦的傷害是獨立事件。

問題:
1. 如果此病的發生率在年輕男性族群為0.2，計算以下狀況對疾病診斷的陽性預測值
-- 只有結果一為陽性
-- 只有結果二為陽性
-- 結果一為陽性但結果二為陰性
-- 結果二為陽性但結果一為陰性
-- 二都都是陽性
-- 二個都是陰性

2. 若是在不知道發生率的情況下，計算和Q1相同的檢查結果下，對疾病診斷的預測(這邊應該要用LR來算)

(純粹惡搞 不附解答)

專業版(誤)

26 year old man presented with some dementia symptoms and signs. Dr. 囧rz think he had MAD (Military Associated Dementia) by history. There are two results after evaluation patient's brain function, each of them had sensitivity and specificity, see as follows:

result 1：patient's left hemisphere had nothing right. Sen:85%, Spe: 40%
result 2： patient's right hemisphere had nothing left.Sen:45%, Spe: 90%

We assume left and right hemisphere damage was independent episode in this disease.

Question:
1. If prevalence was 0.2 in young male population, Calculated the possibility in each condition:
-- only result 1 positive
-- only result 2 positive
-- result 1 positive and result 2 negative
-- result 1 negative and result 2 positive
-- both are negative
-- both are positive

2. if no prevalence data, calculated the possibility in each condition as Q1.