Table A3.1 Normalised Costs: Traditional and PPP projects: Statistical results

Time

Cost

Full period

Stage 1

Stage 2

Stage 3

Full period

Stage 1

Stage 2

Stage 3

PPPs

Average

1.17

1.15

1.12

1.01

1.24

1.22

1.08

1.04

Standard Deviation

0.23

0.26

0.23

0.20

0.53

0.47

0.17

0.08

Variance

0.05

0.07

0.05

0.04

0.28

0.22

0.03

0.01

No of samples

16

16

12

18

10

15

10

10

No of projects > 5% over

8

6

6

5

4

7

5

3

% projects > 5% over

0.50

0.38

0.50

0.28

0.40

0.47

0.50

0.30

Test for bias

Lower

0.94

0.93

0.93

0.95

0.83

0.88

0.95

0.97

Upper

1.06

1.07

1.07

1.05

1.17

1.12

1.05

1.03

Traditional projects

Average

1.15

0.96

1.18

1.26

1.52

1.38

1.20

1.18

Standard Deviation

0.45

0.27

0.25

0.42

1.55

1.09

0.53

0.58

Variance

0.20

0.07

0.06

0.18

2.40

1.19

0.28

0.33

No of samples

14

14

12

21

30

30

33

30

No of projects > 5% over

8

4

6

11

17

15

16

13

% projects > 5% over

0.57

0.29

0.50

0.52

0.57

0.50

0.48

0.43

Test for bias

Lower

0.88

0.93

0.93

0.91

0.72

0.80

0.91

0.89

Upper

1.12

1.07

1.07

1.09

1.28

1.20

1.09

1.11