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
