=+Mining Sci., 2013: 55–60) used a logistic regression model to predict pillar stability. The article reported the following data on x1 5 pillar height to width ratio, x2 5 pillar strength to stress ratio, and pillar stability for 29 coal pillars.

ID x1 x2 Stable? | ID x1 x2 Stable?

1 1.80 2.40 Y | 10 3.59 5.55 Y 2 1.65 2.54 Y | 11 8.33 2.58 Y 3 2.70 0.84 Y | 12 2.86 2.00 Y 4 3.67 1.68 Y | 13 2.58 3.68 Y 5 1.41 2.41 Y | 14 2.90 1.13 Y 6 1.76 1.93 Y | 15 3.89 2.49 Y 7 2.10 1.77 Y | 16 0.80 1.37 N 8 2.10 1.50 Y | 17 0.60 1.27 N 9 4.57 2.43 Y | 18 1.30 0.87 N ID x1 x2 Stable? | ID x1 x2 Stable?

19 0.83 0.97 N | 25 0.94 1.30 N 20 0.57 0.94 N | 26 1.58 0.83 N 21 1.44 1.00 N | 27 1.67 1.05 N 22 2.08 0.78 N | 28 3.00 1.19 N 23 1.50 1.03 N | 29 2.21 0.86 N 24 1.38 0.82 N |