So that they won't mistakenly repeat experiments and waste time. Not keeping data would prevent us from ever advancing anything.
because of the large data simple
Emotions.
They come up with a conclusion to the hypothesis
Draw a conclusion
To eliminate the possibility of hidden or unknown variables the scientist must a control experiment.
Scientists repeat experiments for reliability. The experiment must be repeated for the scientist to develop a theory. One experiment does not prove your hypothesis correct; therefore, it must be done a several times.
To ensure your experiment is fair, you must keep all variables constant except for the one you are testing. This means controlling outside factors that could influence the results of your experiment.
To gather data, you must observe the subject in whatever experiment you are conducting.
Scientists repeat experiments for reliability. The experiment must be repeated for the scientist to develop a theory. One experiment does not prove your hypothesis correct; therefore, it must be done a several times.
A theory is useless if it cannot be tested and verified/disproven. That is the purpose of experiments.
The constant/experimental constant.
If they are supposed to affect the results in the experiment ie. they are what is being tested, they are the test variables. If they must be kept the same to ensure a fair test ie. the scientist is not testing with them, they are called control variables.