false positive

 Longman Dictionary of Contemporary English 5++朗文当代英语 5++LDOCE 5++朗文 5++ˌfalse ˈpositive noun [countable]  something that is wrongly thought or shown to be a particular thing, especially after a scientific test or research 假阳性；错误判断〔尤指科学试验或研究结果〕 50% of the 170 compounds were judged to be carcinogenic, but some of these might be false positives. 这170种化合物中有50%被断定致癌，但有些可能是判断错误。 Many substances give false positive reactions in allergy skin testing. 许多物质在皮肤过敏试验中出现假阳性反应。

ˌfalse ˈpositive nounChineseSyllable  

false positive
ˌfalse ˈpositive noun [countable]
something that is wrongly thought or shown to be a particular thing, especially after a scientific test or research:
    50% of the 170 compounds were judged to be carcinogenic, but some of these might be false positives.
    Many substances give false positive reactions in allergy skin testing.