What is important about a controlled expirement?

Question

What is important about a controlled expirement?

Answer 1

It should be done in a way that is repeatable.

For instance if you were measuring a pH of a solution was the meter calibrated, did you use reagent grade materials, etc.

It is important that another researcher would repeat the results that you got.

Answer 2

It must be controlled to remove variables which make the results unreliable.

For example you are trying to find the best fertilizer for a plant.

All the plants should be in the same condition when you start all equally healthy and the same size, all must get the same amount of sunlight and water, exactly. That is what a controlled environment or experiment means.

The water, sunlight and original condition of the test subject (being the plant) are all considered variables.

How would you know which fertilizer actually worked best if some plants got more sunlight or water then others? Or if some were more healthy to being with. It would invalidate your findings.

Experiments need to be controlled meaning removing any variables.

Answer 3

You personally don't want to be part of the ongoing reaction(s).