A research to find the cause and effect relationship of various phenomena. This type of research must be to control the variable tree. To observe the change of variables to know what causes that result in.
The research to find the cause and effect relationship of the various phenomena of this type of research needs to be controlled variables. According to the variable changes to be made aware of what is causing the effect.
A research to find the cause and effect relationship of various phenomena research of this type must have control of variable plant. To observe the change of variables according to knowing what is causing that causes.