Hypothesis

Another common mistake is to ignore or rule out data which do not support the hypothesis. | Ideally, the experimenter is open to the possibility that the hypothesis is correct or incorrect. | Sometimes, however, a scientist may have a strong belief that the hypothesis is true (or false), or feels internal or external pressure to get a specific result. | In that case, there may be a psychological tendency to find "something wrong", such as systematic effects, with data that do not support the scientist's expectations, while data that do agree with those expectations may not be checked as carefully. | The lesson is that all data must be handled in the same way.