Question

A local trucking company fitted a regression to relate the travel time (days) of its shipments as a function of the distance traveled (miles). The fitted regression is Time = −7.126 + .0214 Distance, based on a sample of 20 shipments. The estimated standard error of the slope is 0.0053. Find the critical value for a right-tailed test to see if the slope is positive, using α = .05.

Answer 1

Thus; the slope is positive

Explanation:

Given that :

the sample size = 20

for the slope; the degree of freedom df = n - 2

= 20 -2

= 18

Using ∝ = 0.05

From t -table , one tailed, at df =18)

`t_(\alpha , df)}= t_(0.05, df = 18) = 1.734`

Thus the t- critical for the right tailed test is 1.734. This simply refers to the fact that the critical region is test statistics.

Incorporating the Excel Formula [ T.INV (1 - 0.05).18) = 1.734063607

≅ 1.734