what do false negative and false positive in medical technology mean?

[قطرة ندى]

:sm199:السلام عليكم :
what means by : false negative and false positive in medical technology
ولكم جزيل الشكر

[dr.moz]

sensitivity = probability of a positive test among patients with disease so when we say the test have 80% sensitivity so there is a chance of 20% of false Negative due to other factors which my affect the test

specificity = probability of a negative test among patients without disease we say the test have 80% specificity so there is a chance of 20% of false positive due to other factors which my affect the test