Confidence interval for a coefficient Suppose we want to compute a 90% confidence interval for β2,...

Confidence interval for a coefficient

Suppose we want to compute a 90% confidence interval for β2, the coefficient of x₂. From Figure 9-21, we have (rounding to three digits after the decimal)

b₂= 0.338, S₂= 0.099, and d.f. = 4

From the t table (Table 6), we find , so, t = 2.132

b2 - tS₂< β₂< b2 + tS₂

0.338 - 2.132(0.099) < β₂< 0.338 + 2.132(0.099)

0.127 < β₂< 0.549