What investigations allow for the control of variables

Dependent - - is what will be measured; it's what the investigator thinks will be affected during the experiment.

For example, the investigator may want to study coffee bean growth. Possible dependent variables include: number of beans, weight of the plant, leaf surface area, time to maturation, height of stem.

Independent - - is what is varied during the experiment; it is what the investigator thinks will affect the dependent variable.

In our coffee bean example, possible independent variables include: amount of fertilizer, type of fertilizer, temperature, amount of H2O, day length, all of these may affect the number of beans, weight of the plant, leaf area, etc.