Keep the results a secret. Do the math without a calculator. Change all of the variables in the experiment. Ask other scientists to attempt to reproduce the results.
I gave my students this multiple choice question: What should a scientist do to help make sure the results of an experiment are unbiased?

Only one answer is correct among these 4 choices:
- Keep the results a secret.
- Do the math without a calculator.
- Change all of the variables in the experiment.
- Ask other scientists to attempt to reproduce the results.

Could you tell me which one is correct?

Ask other scientists to attempt to reproduce the results.