You have to remove yourself from any personal interest in the subject. This is not easy to do. With strict discipline it is possible however. Just remember that true science accepts all possible outcomes, not just the ones you want.
Using double-blind procedures where both the experimenter and participants are unaware of the group assignments can help correct for experimenter bias. This helps ensure that the results are not influenced by the experimenter's expectations or behavior. Additionally, having clear operational definitions, standardized protocols, and using randomization can also help minimize experimenter bias.
Experimenter Bias, also known as Experimenter Expectancy, is made up of all the things an experimenter might unwittingly do to influence the results of an experiment to resemble his hypothesis. You could consider this a self-fulfilling prophecy to some extent.
In science, bias is an undesirable property, whose presence may not be recognized by the experimenter. A maladjusted measuring standard would produce such an error. In intellect tests, cultural bias may be very difficult for the experimenter to recognize.
A preference towards a result expected by the human experimenter
People who perform experiments take some care to avoid introducing their personal bias into the results. But even if there is a bias, the same experiment may be done by other people who have other biases or who are more successful in working in an unbiased manner. Eventually, truth will emerge.
experimental bias
When someone wants the results of an experiment to come out a certain way, it is called experimenter bias or confirmation bias. This can lead to skewed results and undermine the validity of the experiment.
Replication reduces the chances that findings are due to experimenter bias, methodological flaws, or sampling errors
Conducting the study as a double blind. ie. the participants don't know which group they're in but nor does the researcher.
Double-blind testingRandom Assignment
In single blind studies, the experimenter (or observer) is aware of who or what belongs to the control group and the experimental group.In double blind studies, the experimenter is not aware of who/what belongs to which group. This is to eliminate the subjective bias an experimenter may have.
You need to avoid bias when you're a teacher.Because of the bias in his study, the results were rejected.