Читать книгу Introduction to Linear Regression Analysis - Douglas C. Montgomery - Страница 33

We test for significance of regression in the rocket propellant regression model of Example 2.1. The estimate of the slope is , and in Example 2.2, we computed the estimate of σ² to be . The standard error of the slope is

Therefore, the test statistic is

If we choose α = 0.05, the critical value of t is t_0.025,18 = 2.101. Thus, we would reject H₀: β₁ = 0 and conclude that there is a linear relationship between shear strength and the age of the propellant.