Science experiments have two main types of variables: the dependent variable and the independent variable. The independent variable is the variable that scientists manipulate intentionally to cause potential change in the experimental system. The dependent variable is the thing that scientists monitor. An experiment can have multiple independent variables, but the scientist must take care when analyzing the relationships between all of the variables involved.
The Causality of Scientific Variables
In order to establish a causal relationship between independent and dependent variables, scientists must be sure that no other factors cause the dependent variable to change. One way of accomplishing this is to vary only one independent variable at a time. If scientists change only one variable and observe a corresponding change in a dependent variable, they can begin to establish some causal mechanism between the two. It is also possible to analyze the effects of multiple independent variables at once. This technique is called multiple regression .
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