Experimental Design Case 4 The experimenter had observed that some colors of birthday balloons seem to be harder to inflate than others. She ran this experiment to determine whether balloons of different colors are similar in terms of the time taken for inflation to a diameter of 7 inches. Four colors were selected from a single manufacturer. An assistant blew up the balloons and the experimenter recorded the times (to the nearest 1/10 second) with a stop watch. Questions for all the following cases: Please identify: Independent variable and number of level? Dependent variable? Study design (i.e., between or within-subject design)? Confounding variable (if any)? Violation of Validity (if measureable)?