The problem of negatives in chemistry is complicated.
Sometimes the negatives (or positives) are due to experimental problems (clogged pipette, a drop of something that jumped from another well, a defect in a plate...) or to artifacts (your reaction detection mechanism gets impacted by something in your reagents not the final products). There are ways to go around that, but in many High throughput screening approaches at least for the first step when you have millions of samples you don't do as many controls as possible because of cost and time.
There is a lot of complexity in wet science such as purity of your reagents or degradation which if you lack quality controls (because of cost or sloppyness) makes you not trust the results of other groups than yours.
A lot of HTS programs I saw in the pharma industry they would screen stuff and then look at what it is because after decades in DMSO in a fridge, clerical errors and experimental mistakes a lot of molecules weren't what it was supposed to be.
Sometimes the negatives (or positives) are due to experimental problems (clogged pipette, a drop of something that jumped from another well, a defect in a plate...) or to artifacts (your reaction detection mechanism gets impacted by something in your reagents not the final products). There are ways to go around that, but in many High throughput screening approaches at least for the first step when you have millions of samples you don't do as many controls as possible because of cost and time.
There is a lot of complexity in wet science such as purity of your reagents or degradation which if you lack quality controls (because of cost or sloppyness) makes you not trust the results of other groups than yours.
A lot of HTS programs I saw in the pharma industry they would screen stuff and then look at what it is because after decades in DMSO in a fridge, clerical errors and experimental mistakes a lot of molecules weren't what it was supposed to be.