controlled factor
nounUK /kənˈtrəʊld ˈfæktə/
US /kənˈtroʊld ˈfæktər/
A controlled factor is something a scientist keeps the same in a test so it does not change the result.
The scientist kept the temperature as a controlled factor so the plants all grew in the same warmth.
OTHER MEANINGS
2. A condition in a machine or system that is deliberately kept steady.
In the factory, humidity is a controlled factor for making computer chips.
3. Something in a game or sport that players cannot change, so everyone plays fairly.
The size of the field was a controlled factor in the tournament.
4. A part of a recipe or process that is measured exactly the same each time.
The amount of sugar was a controlled factor in every batch of cookies.