In a study of the production function of the United Kingdom, bricks, pottery and glass

industry for the period 1961 - 81, researchers obtained the following results

Log Q = -8.57 + 0.272t + 0.460 log K + 1.285log H

Se = (1.40) (0.087) (0.137) (0.324) R^2=0.878

verify that the coefficients of t and log K are individually insignificant at the 5% level.

My Attempt:

t, t.s = (0.272-0)/0.087 = 3.1264 K, t.s = (0.460-0)/0.137 = 3.3577

C.V = t0.05/2, 20-1

= 2.093

is |3.1264| & |3.3577| > C.V, and therefore insignificant.

Is my degrees of freedom wrong. Gah, what am I doing wrong!

Thanks for the help