Hi Ziba,

No, not every study has independent and dependent variables; these terms apply when you want to test the effect of one variable upon another.

Other types of studies sometimes use other terms, such as predictor and outcome variables or explanatory and response variables. In your example, we might say that “weight” is the outcome variable, while “athlete status” (i.e. athlete or non-athlete) is the predictor variable.

Hi John,

Yes, you’re correct that in this example, plant species would be a moderating variable.

In an experiment, the independent variable is the one that you directly manipulate (in this case, the amount of salt added). A moderating variable is one that you measure because it might influence how the independent variable acts on the dependent variable, but which you do not directly manipulate (in this case, plant species). You can read more in our article about moderating variables.

Hope that helps!

Im sorry, i meant moderating variable as plant species and independent variables as Salt added.

Is it appropriate to put it this way?

Can we put in this way, Plant species as independent and Salt Added as moderating variable? Since different plant species gives out different outcome in the dependent variable section. Is it appropriate to say that plant species is an independent variable too?

Thank you.