Numerous  factors  contribute  to  the  smooth  running  of  an electric motor (“Increasing Market Share Through Improved Product  and  Process  Design:  An  Experimental  Approach,” Quality  Engineering,  1991:  361–369).  In  particular,  it  is desirable to keep motor noise and vibration to a minimum. To study the effect that the brand of bearing has on motor vibration, five different motor bearing brands were examined by installing each type of bearing on different random sample of seven motors. The amount of motor vibration (measured in microns) was recorded when each of the 35 motors was running. The data for this study follows. State and test the relevant hypotheses at significance level .05, and then carry out a multiple comparisons analysis if appropriate. Should one continue to Tukey test ? Why ? Do it Or Why not ? If Ho is rejected, perhaps one or more brands are significantly different, do a Tukey analysis.

                                           (samples 1 - 7)

Brand    1         2          3          4             5          6           7