Good experimental design exercise-3


Stephen was given 4 different balls by his sports teacher and asked to find out which one has the most bounce. Stephen set up 8 different tests and measured the height each ball was dropped from and the height it reached after bouncing off the floor boards of the gym. He recorded his results in the table shown below. All balls were dropped vertically onto the floor boards.
Test
Type of ball
Height from which the ball was dropped (m)
Height of bounce(m)
1
Tennis
1.0
0.60
2
Tennis
1.5
0.75
3
Table tennis
2.0
0.96
4
Table tennis
1.5
0.73
5
Squash
1.5
0.22
6
Squash
0.8
0.13
7
Soccer
3.0
1.78
8
Soccer
1.5
0.86

 

What is the aim of Stephen's tests?

Which four tests should Stephen use so that a fair comparison can be made between the four balls? Explain.
Solution

What are the variables that should remain constant for all tests in Stephen's experiment?

Irene suggested to Stephen that his tests are unfair and that he should conduct his experiment during a hot day because the balls will bounce higher. Comment on this suggestion.
Solution

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