13.18 The paper “The Effects of Split Keyboard Geometry on Upper Body Postures” (Ergonomics [2009]: 104–111)

describes a study to determine the effects of several keyboard characteristics on typing speed. One of the variables considered was the front-to-back surface angle of the keyboard. Minitab output resulting from fitting the simple linear regression model with x 5 surface angle (degrees) and y 5 typing speed (words per minute) is given below.

Regression Analysis: Typing Speed versus Surface Angle The regression equation is Typing Speed 5 60.0 1 0.0036 Surface Angle Predictor Coef SE Coef T P Constant 60.0286 0.2466 243.45 0.000 Surface Angle 0.00357 0.03823 0.09 0.931 S 5 0.511766 R -Sq 5 0.3% R-Sq(adj) 5 0.0%

Analysis of Variance Source DF SS MS F P Regression 1 0.0023 0.0023 0.01 0.931 Residual Error 3 0.7857 0.2619 Total 4 0.7880

a. Assuming that the basic assumptions of the simple linear regression model are reasonably met, carry out a hypothesis test to decide if there is a useful linear relationship between x and y. (Hint: See Example 13.5.)

b. Are the values of se and r2 consistent with the conclusion from Part (a)? Explain.