The article “Creep and Fatigue Characteristics of Ferrocement Slabs” (J. Ferrocement, 1984: 309–322) reported data on y

tensile strength (MPa), x1
slab thickness (cm), x2
load

(kg), x3
age at loading (days), and x4
time under test

(days) resulting from stress tests of n
9 reinforced concrete slabs. The results of applying the BE elimination method of variable selection are summarized in the accompanying tabular format. Explain what occurred at each step of the procedure.

Step 1 2 3 Constant 8.496 12.670 12.989 x1 .29 .42 .49 T-RATIO 1.33 2.89 3.14 x2 .0104 .0110 .0116 T-RATIO 6.30 7.40 7.33 x3 .0059 T-RATIO .83 x4 .023 .023 T-RATIO 1.48 1.53 S .533 .516 .570 R-SQ 95.81 95.10 92.82