Refer to the water-discharge data given in Exercise 55 and let , and . Consider fitting the model .

a. The resulting hii’s are .138, .302, .266, .604, .464, .360,

.215, .153, .214, and .284. Does any observation appear to be influential?

b. The estimated coefficients are and , and the corresponding estimated standard deviations are , and .

The second standardized residual is . When the second observation is omitted from the data set, the resulting estimated coefficients are , and

. Do any of these changes indicate that the second observation is influential?

c. Deletion of the fourth observation (why?) yields

, and . Is this observation influential?

bˆ b 2 5 .1515 ˆ

0 5 1.4592, bˆ

1 5 .9850 bˆ

2 5 .3085 bˆ

0 5 1.8982, bˆ

1 5 1.025 e2

* 5 2.19 sbˆ sbˆ 2 5 .1752 0 5 .7328, sbˆ

1 5 .1528 bˆ

2 5 .1815 bˆ

0 5 1.5652, bˆ

1 5 .9450, Y 5 b0 1 b1x 1 1