matched pairs design by cmFSb53

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									                Completely Randomized versus Matched Pairs Experiment

        Comparing Hand Strength: Is the right hand generally stronger than the left in
        right-handed people? You can crudely measure hand strength by placing a
        bathroom scale on a shelf with the end protruding, then squeezing the scale
        between the thumb below and the four fingers above it. The reading of the scale
        shows the force exerted.” [BPS/page 198/problem 3.43]

        1. Diagram a completely randomized experiment to compare the strength of the
           right and left hands, using 10 right-handed people as subjects.

        2. Diagram a matched pairs experiment to compare the strength of the right and
           left hands, using 10 right-handed people as subjects.

        3. Which of the two designs is appropriate? Why.




                         Completely Randomized Experiment
                R
                a
                n
                d
                o
                                                                   Average
                      Group 1            Measure left hand         left hand
                m
                         (5)
 Available                                                         measures
                A
  group of
                s                                                                         Compare
patients (10)   s
                i
                                                                                          averages
                g                                                   Average
                       Group 2
                n                         Measure right            right hand
                         (5)
                m                            hand                   measures
                e
                n
                t




                 R               Match Pairs Experiment
                 a
                 n
                 d                      Measure left hand
                 o    Group 1              first, then
                         (5)                                             For each
 Available
                 m                         right hand
                                                                          subject,
  group of                                  sesecond                                        Compare
                 A                                                    subtract right
patients (10)    s                                                    hand from left         to zero
                 s                                                    hand and take
                 i                        Measure right
                 g    Group 2             hand first, then           average of that
                 n      (5)                  left hand               list of numbers
                 m
                 e
                 n
                 t

								
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