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May 16, 2006 - Skitmore, R.M. and Ng, T. (2001) Australian project time-cost analysis: statistical analysis ... In the first part of this paper, we examine a set of 1990s completed building projects .... The Australian Institute of Quantity Surveyors,.
COVER SHEET

Skitmore, R.M. and Ng, T. (2001) Australian project time-cost analysis: statistical analysis of intertemporal trends. Construction Management and Economics 19(5):pp. 455-458.

Copyright 2001 Taylor & Francis Accessed from: https://eprints.qut.edu.au/secure/00004149/01/Years4.doc

Paper for

Construction Management and Economics

Australian project time-cost analysis: statistical analysis of intertemporal trends

Martin Skitmore 3 Thomas Ng 1 3

1

School of Construction Management and Property, Queensland University of Technology, Gardens Point, Brisbane Q4001, Australia.

Department of Civil Engineering, University of Hong Kong, Pokfulum, Hong Kong.

Please contact: Professor Martin Skitmore School of Construction Management and Property Queensland University of Technology Gardens Point Brisbane Q4001 Australia E-mail: [email protected]

16 May 2006

ANALYSIS OF INTERTEMPORAL PROJECT TIME-COST TRENDS ABSTRACT

In investigating intertemporal movements in time-cost relationships via the Bromilow model, it is shown that, with a recently collected sample of data from the Australian State of New South Wales, the constant term in the linearised regression equation is not significantly (p 20 %

10 to 20 %

0

-10 to -20 %

> -20%

33

15

33

5

7

≤1

1 - 10

10 - 50

50 - 100

> 100

20

51

13

5

4

> 20 %

10 to 20 %

0

-10 to -20 %

> -20%

21

42

24

4

2

Table 1: Details of projects surveyed

12

With constant Year

N

1992

Without constant

α0

p

α1

p

AdjR2

SEE

α1

p

AdjR2

SEE

4

0.874

0.768

0.266

0.222

0.408

0.394

0.317

0.000

0.996

0.332

1993

2

-

-

-

-

-

-

-

-

-

-

1994

4

0.282

0.811

0.315

0.038

0.887

0.331

0.332

0.000

0.997

0.275

1995

8

0.850

0.667

0.292

0.053

0.407

0.539

0.347

0.000

0.991

0.507

1996

16

1.030

0.424

0.273

0.006

0.380

0.344

0.343

0.000

0.995

0.340

1997

25

1.632

0.041

0.256

0.000

0.515

0.444

0.362

0.000

0.993

0.476

1998

30

-0. 848

0.332

0.403

0.000

0.607

0.368

0.345

0.000

0.995

0.367

1999

4

2.036

0.640

0.225

0.393

0.052

0.275

0.368

0.000

0.998

0.240

Total

93

0.548

0.160

0.311

0.000

0.583

0.427

0.349

0.000

0.993

0.429

Table 2: Summary of regression models for NSW data

13

Ratios

SS effect

df

MS effect

SS error

df

MS error

F

p

All

0.01457

7

0.00208

0.06461

85

0.00076

2.738

0.013

1995-8

0.00739

3

0.00246

0.06173

75

0.00802

2.992

0.036

1996-8

0.00733

2

0.00367

0.05264

68

0.00077

4.732

0.012

Table 3: Analysis of variance

Source

Public

Data

This survey 1988 survey (Bromilow et al, 1988) 1983 survey (Ireland, 1983) Post 1974 projects survey (Bromilow and Henderson, 1977) Pre 1974 projects survey (Bromilow and Henderson, 1977) 1969 survey (Bromilow, 1969)

Private

Overall

K

B

K

B

K

B

1992-99

129

0.32

132

0.30

131

0.31

1976-81

186

0.38

136

0.28

164

0.30

1980

-

-

-

-

155

0.47

1974-6

286

0.34

160

0.37

-

-

1970-4

199

0.28

137

0.28

-

-

1964-7

211

0.30

156

0.30

177

0.30

Note: values updated to March 1998 prices

Table 4: K and B values of research studies

Source This survey 1988 survey (Bromilow et al, 1988) 1983 survey (Ireland, 1983) Post 1974 projects survey (Bromilow and Henderson, 1977) Pre 1974 projects survey (Bromilow and Henderson, 1977) 1969 survey (Bromilow, 1969)

Assumed average

Public

Private

Overall

1996

0.346

0.348

0.345

1981

0.379

0.342

0.357

1980

-

-

0.384

1975

0.397

0.338

0.387

1972

0.364

0.342

0.355

1966

0.372

0.354

0.361

Table 5: Estimated B’ values of research studies

14

Var

N

α0

p

α1

p

R2

F(1,4)

p

SEE

B’

6

1.5106

0.379

-0.00773

0.4951

0.123

0.5619

0.4952

0.177

Table 6: Regression results for previous studies

15

16

17

18