An antibody test gives a scalar value of how much antibodies there are. If you want to go from a scalar value to a binary value you have to decide on a cutoff that switches from infected to -not-infected.
Given even a tiny bit of test inaccuracy, when the amount of antibody reaction is right at your cutoff, you will have 50% showing infected and 50% showing not not-infected.
An antibody test gives a scalar value of how much antibodies there are. If you want to go from a scalar value to a binary value you have to decide on a cutoff that switches from infected to -not-infected.
Given even a tiny bit of test inaccuracy, when the amount of antibody reaction is right at your cutoff, you will have 50% showing infected and 50% showing not not-infected.
Got it, thank you!