The factors that must remain the same in an experiment are known as control variables.
In order to conduct a proper experiment, there must be 3 kinds of variables. These are:
A dependent variable is a variable that the experiment seeks to observe, this variable is expected to change in value throughout the experiment and depends on other variables. An independent variable is one that the researcher changes throughout the experiment in order to see what effect it will have on the dependent variable.
The variables referred to in the question are control variables. Control variables are the factors that must remain constant in an experiment. This is to ensure that when we measure a change in the dependent variable, we know to attribute it to the correct cause of the change. The presence of control variables helps to ensure a valid experiment and limits the influence of other factors on the outcome.
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