Question

Use the same data set for particle board stiffness as in question 3

Density	Stiffness	Temp
9.5	14.81	70.6
8.4	17.50	73.3
9.8	14.01	66.2
11	19.44	70.1
8.3	7.57	69.3
9.9	14.19	69.1
8.6	9.71	69.8
6.4	8.08	64.4
7	5.30	65.4
8.2	10.73	67.8
17.4	43.24	69.7
15	25.32	66.9
15.2	28.03	71.5
16.4	41.79	66.6
16.7	49.50	68.0
15.4	25.31	64.3
15	26.22	64.5
14.5	22.15	71.3
14.8	26.75	69.6
13.6	18.04	71.1
25.6	96.31	72.1
24.4	72.59	67.3
23.3	49.51	66.7
19.5	32.21	68.1
21.2	48.22	66.5
22.8	70.45	65.7
21.7	47.66	66.3
19.8	38.14	69.4
21.3	53.05	68.3

1. Obtain a fitted line plot from Minitab assuming we are trying to predict the stiffness of the particle board from its density. Comment on the relationship you see.
2. State the hypothesis we should use to determine if there is an association between these variables.
3. Run the appropriate test is Minitab and show the Minitab output.
4. State your conclusions about the strength of this relationship if we use a 5% level of significance.
5. Are the assumptions satisfied? Provide appropriate plots to prove it and comment what the plots show you.
6. Calculate a 95% confidence on the slop of the regression line and interpret what it means.
7. Obtain from Minitab a 95% confidence interval on the average stiffness at a density of 8.5 and explain what the interval means.
8. Obtain from Minitab a 95% prediction interval on the stiffness of a run of particle board for which its density is 7.8, and explain what the interval means.

Answer 1