The initial observation is that Gary is suffering from slimtosis.
The independent variables would be the seaweed that is rubbed on Gary and the Dr. Kelp that Gary drinks.
The dependent variable would be the amount of smell produced by Gary.
This lab is inconclusive because two variables were applied to Gary in order to rid him of the slimtosis. It is not possible to conclude whether the seaweed rub or Dr. Kelp drink cured Gary of his ailment.
In an experiment, the independent variable is the variable that is changed by the scientist. For this reason, the independent variable is sometimes referred to as the manipulated variable. In order for a scientist to accurately determine what causes a change to occur within his or her lab, scientific experiments should contain only one independent variable.
The dependent variable of an experiment is the variable that is measured. It is the variable that is affected by the independent variable. For this reason, dependent variables are sometimes referred to as “responding variables."