Source

Value

Standard error

t

Pr > |t|

Lower bound (95%)

Upper bound (95%)

Intercept

−12.355

6.805

−1.816

0.073

−25.901

1.190

Dia

−0.489

0.102

−4.795

<0.0001

−0.692

−0.286

Age

0.008

0.012

0.725

0.471

−0.015

0.032

Sand

3.144

0.891

3.528

0.001

1.370

4.918

Clay

0.000

0.000

Low Traffic

1.151

1.546

0.744

0.459

−1.926

4.227

Heavy Traffic

5.961

2.107

2.830

0.006

1.768

10.154

Trees

−2.819

1.236

−2.280

0.025

−5.280

−0.359

no trees

0.297

1.134

0.262

0.794

−1.959

2.554

shallow unde 6

0.580

1.034

0.561

0.576

−1.478

2.639

deep bury

0.000

0.000

pressure

0.194

0.119

1.625

0.108

−0.044

0.431

Ductile

2.342

0.640

3.658

0.000

1.068

3.617

GI

5.473

0.598

9.151

<0.0001

4.282

6.663

PVC

3.229

0.717

4.501

<0.0001

1.801

4.657

AC

12.428

0.757

16.408

<0.0001

10.920

13.935

HDPE

0.000

0.000