Drake is comparing time people spend playing games on Xbox versus Playstation. In his study, individuals ages 10 - 15 are given Xbox's and individuals ages 16 - 25 are given Playstations. After collecting his data he observes that those using the Playstation had logged more hours. Drake concludes that the Playstation is more popular. This is an example of :
A. experimental bias
B. skepticism
C. controlled environment
D. a qualitative observation

Two 8th grade students decided to race around the track at their school. One had running shoes on and the other student was wearing sandals. Their running speed was compared. What is the dependent variable?
A. Types of shoes
B. Age of the students
C. Speed of the students
D. Distance the students ran

His experiment included the people of the age of 10 - 15 and 16 - 25 years by providing Xbox's to the people of 10 - 15 years and Play-stations to the 16 - 25 years.

This is a case of experimental bias as his investigation was a comparative analytical investigation which should be performed between the same group and the independent variable provided should also be the same Also it lacked the control group.

Thus, option-A is the correct answer.

Case II

In the given case, the researcher compared the speed of two 8th grade students by providing running shoes to one student and sandals to another.

This experimental design included the dependent variable as the speed of the students as the speed is the variable which is being tested in the experiment.

Thus, option-C is the correct answer.