This may be the author’s version of a work that was submitted/acceptedfor publication in the following source:

Skitmore, Martin & Patchell, Brendon(1990)Developments in contract price forecasting and bidding techniques.In Brandon, Peter (Ed.) Quantity Surveying Techniques : New Directions.BSP Professional Books, Oxford, pp. 75-120.

This file was downloaded from: https://eprints.qut.edu.au/60104/

c© Copyright 1990 [please consult the author]

This work is covered by copyright. Unless the document is being made available under aCreative Commons Licence, you must assume that re-use is limited to personal use andthat permission from the copyright owner must be obtained for all other uses. If the docu-ment is available under a Creative Commons License (or other specified license) then referto the Licence for details of permitted re-use. It is a condition of access that users recog-nise and abide by the legal requirements associated with these rights. If you believe thatthis work infringes copyright please provide details by email to qut.copyright@qut.edu.au

Notice: Please note that this document may not be the Version of Record(i.e. published version) of the work. Author manuscript versions (as Sub-mitted for peer review or as Accepted for publication after peer review) canbe identified by an absence of publisher branding and/or typeset appear-ance. If there is any doubt, please refer to the published source.

Figu

re 1

(a)

Regr

essio

n ou

tput

at s

tep

3

Figu

re 1

(b)

Regr

essio

n ou

tput

at s

tep

3

Figu

re 1

(c) R

egre

ssio

n ou

tput

at s

tep

3

Figu

re 1

(d) R

egre

ssio

n ou

tput

at s

tep

3

Table 1: Resume of estimating techniques

Contract Standardised number contract

sum*

Gross floor

Number of

Air- conditioning

Contract period

Number of

area (m2)

storeys (0 = no) (1= yes)

(months) tenders

CASENO CONSUM GFA STOREY ACOND PERIOD BIDDERS

1 1085.95 452 2 0 8 6 2 5042.91 1601 7 0 11 8 3 2516.59 931 3 1 11 7 4 18290.60 6701 7 1 17 6 5 3195.81 219 3 0 12 1 6 8894.68 3600 6 0 15 9 7 932.06 490 2 0 7 6 8 979.93 415 1 0 8 8 9 1684.94 504 3 0 9 6 10 1896.39 320 2 0 7 7 11 3789.05 372 2 0 6 7 12 2445.12 837 2 0 9 4 13 1501.91 491 3 0 6 6 14 1114.31 496 1 0 6 6 15 943.48 430 2 0 99 99 16 3670.98 1368 4 0 12 4 17 1094.75 469 2 0 6 4 18 4584.87 1260 2 0 8 5 19 10942.28 2994 8 1 15 1 20 760.29 312 2 0 6 6 21 3002.67 1225 2 0 9 7 22 2720.44 1230 2 0 10 8 23 58365.39 23089 7 1 20 7 24 11323.40 4273 4 1 20 7 25 37 357.91 11300 5 1 18 6 26 46309.12 14430 3 1 30 6 27 1704.17 437 3 1 10 9 28 6792.04 2761 5 1 12 6

Contract sum ÷ tender price index ÷ location factor e.g. contract number 2 contract sum = 1514385÷ in London (location factor 1.30) on Sept 1987 (TPI 231). Standardised contract sum = 514385 + 231 ÷1.30 = 5042.91

Table 2: Regression data

Regression coefficient

Constant Forecast 95% confidence limits for new

forecast

cv

Step 1 BIDDERS

-0.4355

1.8298

1.0495

±0.6844

38.31

Step 2 BIDDERS

-0.4251

GFA -0.0395 2.0929 0.9873 ±0.7090 39.10

Step 3 BIDDERS

- 0.2987

GFA -0.3071 PERIOD 0.8814 1.7040 1.0609 ±0.6011 32.05

Step 4 BIDDERS

-0.2665

GFA PERIOD

·-0.3293 0.8480

STOREY 0.1032 1.7887 1.0634 ± 0.6075 33.99

Step 5 BIDDERS

-0.2646

GFA PERIOD

-0.3253 0.8848

STOREY ACOND

0.1108 -0.0667

1.6847

1.1166

±0.6836

35.06

Table 3: Stepwise regression results