The optimism bias values in Table 3 below represent the average optimism bias levels for each of the project types studied.
Table 3 Recorded Optimism Bias
Project Type | Optimism Bias (%) | |||||
Unitary Payments | ||||||
Traditional* | Non-standard Buildings | 39 | 51 | N/A | No Info | 1 |
Standard Buildings | 4 | 24 | N/A | No Info | No Info | |
Non-standard Civil Engineering | 15 | 66 | N/A | No Info | 5 | |
Standard Civil Engineering | 34 | 44 | N/A | No Info | No Info | |
Equipment/Development | 54 | 214 | N/A | No Info | No Info | |
Outsourcing | N/A | N/A | N/A | 41 | No Info | |
All Traditional | 17 | 47 | N/A | 41 | 2 | |
PFI / PPP** | Standard Buildings | -16 | 2 | 1 | N/A | 0 |
Standard Civil Engineering | No Info | 0 | 0 | N/A | 0 | |
Equipment/Development | 28 | No Info | 19 | N/A | 10 | |
Outsourcing | N/A | N/A | 8 | N/A | 5 | |
All PFI / PPP | -1 | 1 | 5 | N/A | 2 | |
* The optimism bias is measured from strategic outline case or outline business case. ** The optimism bias is measured from full business case. The capital expenditure optimism bias is measured as a percentage of the contract price. | ||||||
Note: Do not use Table 3 for calculating the optimism bias levels for current projects. Guidance for calculating optimism bias levels for current projects is provided in Section 4.
The optimism bias levels for PFI / PPP projects were measured at the full business case stage, whereas the optimism bias levels for traditionally procured projects have been recorded at the strategic outline case and the outline business case stages.