X1 X2

X1

Left-skewed covariate

X2

Right- skewed covariate

D1 binary

(skewness, kurtosis)

Mean

SD

(S, K) Coefficient

SE

Power

Mean

SD

(S, K) Coefficient

SE

Power

Coefficient SE

SE

Power

70

8

β1 = 0.05

160

25

β2 = 0.02

β2 = 0.83

Correlation of (X1, X2) = 0.0

(0.0, 0.0) (0.0, 0.0)

70.0

8.0

(0.0, 0.0) 0.052

0.019

0.774

160.0

24.9

(0.0, 0.0) 0.020

0.006

0.931

0.860

0.304

0.801

(−0.5, 0.5) (0.0, 0.0)

70.0

8.0

(−0.5, 0.5) 0.052

0.020

0.754

160.0

24.9

(0.0, 0.0) 0.020

0.006

0.933

0.864

0.304

0.815

(−1.0, 1.0) (0.0, 0.0)

70.0

8.0

(−1.0, 1.0) 0.053

0.021

0.727

160.0

24.9

(0.0, 0.0) 0.020

0.006

0.933

0.864

0.304

0.818

(0.0, 0.0) (0.4, 0.3)

70.0

8.0

(0.0, 0.0) 0.052

0.019

0.764

160.0

24.9

(0.4, 0.3) 0.020

0.006

0.948

0.861

0.305

0.805

(0.0, 0.0) (0.8, 0.6)

70.0

8.0

(0.0, 0.0) 0.052

0.019

0.766

160.0

24.9

(0.8, 0.6) 0.020

0.006

0.957

0.861

0.306

0.805

(−0.5, 0.5) (0.4, 0.3)

70.0

8.0

(−0.5, 0.5) 0.052

0.020

0.753

160.0

24.9

(0.4, 0.3) 0.020

0.006

0.948

0.863

0.305

0.812

(−1.0, 1.0) (0.8, 0.6)

70.0

8.0

(−1.0, 1.0) 0.053

0.021

0.723

160.0

24.9

(0.8, 0.6) 0.020

0.006

0.955

0.861

0.305

0.816

Correlation of (X1, X2) = 0.3

(0.0, 0.0) (0.0, 0.0)

70.0

8.0

(0.0, 0.0) 0.051

0.020

0.742

160.0

25.0

(0.0, 0.0) 0.021

0.007

0.910

0.871

0.305

0.820

(−0.5, 0.5) (0.0, 0.0)

70.0

8.0

(−0.5, 0.5) 0.052

0.021

0.704

160.0

25.0

(0.0, 0.0) 0.021

0.007

0.910

0.871

0.304

0.830

(−1.0, 1.0) (0.0, 0.0)

70.0

8.0

(−1.0, 1.0) 0.052

0.022

0.665

160.0

25.0

(0.0, 0.0) 0.021

0.007

0.906

0.875

0.306

0.826

(0.0, 0.0) (0.4, 0.3)

70.0

8.0

(0.0, 0.0) 0.052

0.020

0.747

160.0

25.0

(0.4, 0.3) 0.020

0.006

0.922

0.873

0.303

0.827

(0.0, 0.0) (0.8, 0.6)

70.0

8.0

(0.0, 0.0) 0.052

0.020

0.755

160.0

25.0

(0.8, 0.6) 0.020

0.006

0.935

0.874

0.305

0.823

(−0.5, 0.5) (0.4, 0.3)

70.0

8.0

(−0.5, 0.5) 0.052

0.021

0.704

160.0

25.0

(0.4, 0.3) 0.020

0.006

0.926

0.874

0.305

0.829

(−1.0, 1.0) (0.8, 0.6)

70.0

8.0

(−1.0, 1.0) 0.052

0.023

0.662

160.0

25.0

(0.8, 0.6) 0.020

0.006

0.938

0.874

0.305

0.829

Correlation of (X1, X2) = 0.6

(0.0, 0.0) (0.0, 0.0)

70.0

8.0

(0.0, 0.0) 0.052

0.024

0.587

160.0

25.0

(0.0, 0.0) 0.021

0.008

0.779

0.873

0.305

0.817

(−0.5, 0.5) (0.0, 0.0)

70.0

8.0

(−0.5, 0.5) 0.052

0.025

0.542

160.0

25.0

(0.0, 0.0) 0.020

0.008

0.780

0.875

0.304

0.823

(−0.1, 1.0) (0.0, 0.0)

70.0

8.0

(−1.0, 1.0) 0.052

0.027

0.508

160.0

25.0

(0.0, 0.0) 0.021

0.008

0.805

0.875

0.303

0.819

(0.0, 0.0) (0.4, 0.3)

70.0

8.0

(0.0, 0.0) 0.052

0.024

0.595

160.0

25.0

(0.4, 0.3) 0.020

0.007

0.812

0.873

0.307

0.822

(0.0, 0.0) (0.8, 0.6)

70.0

8.0

(0.0, 0.0) 0.052

0.024

0.608

160.0

25.0

(0.8, 0.6) 0.020

0.007

0.844

0.873

0.308

0.815

(−0.5, 0.5) (0.4, 0.3)

70.0

8.0

(−0.5, 0.5) 0.052

0.025

0.557

160.0

25.0

(0.4, 0.3) 0.020

0.007

0.815

0.872

0.305

0.818

(−1.0, 1.0) (0.8, 0.6)

70.0

8.0

(−1.0, 1.0) 0.052

0.026

0.530

160.0

25.0

(0.8, 0.6) 0.020

0.007

0.878

0.869

0.305

0.812