A scientist wishes to test a new type of adhesive to connect two metals together. He tests his hypothesis that the new adhesive works better than existing treatments by applying the adhesive to the two metals, sticking them together and seeing how long they stick. He performs this test on his new adhesive, records the time and then reports the results. What is missing from his experimental design?

The scientific method is a research method used to produce knowledge. It consists of systematic observations, measures, experimentation, analysis, and verification of a hypothesis. It is based on two aspects: reproducibility (the capability of reproducing the experiment in any other place by any researcher) and refutability (susceptibility to be refused).

There are different steps to follow in a scientific method:

• Definition and problem statement. The question for which there is not an answer yet.

• Hypothesis formulation.

• Data collection and analysis. This step involves testing the observations.

• Results

• Verification of the hypothesis. This step involves the acceptance or rejection of the working hypothesis.

• Conclusions and Discussion.

In the exposed example:

Let us imagine that the scientist only wants to evaluate the performance of the new adhesive connecting only two previously determined metals: Metal A and metal B. Let us also assume that there is only one exhisting adhesive, apart from the new one that is being tested. Finally, we might also assume that he has already done bibliographic research to know better about the requirements for adhering metals and the properties of the adhesive material needed to do so. The problem might have been related to the need of getting a better adhesive.

Hypothesis: "the new adhesive works better than existing treatments"
Treatment: applying the adhesive to the two metals, sticking them together and seeing how long they stick

Data collection and analysis: He performs this test on his new adhesive, records the time
Results obtention and report

The scientist did not perform the experiment with the existing adhesive. The scientist did not compare the performance of the previously existing adhesive to the new one.

The scientist should have performed the experiment with two treatment groups:

Treatment Group one: applying the existing adhesive to the metals A and B, sticking them together and seeing how long they stick

Treatment Group two: applying the new adhesive to the metals A and B, sticking them together and seeing how long they stick

The scientist also should have repeated the treatment at least two or three times for each group.

Finally, the scientist should have compared results between the performance of the two adhesives before reporting them.