Estimating processes of smaller builders

The paper describes a study of the way smaller builders price bills of quantities items for competitive tender. A series of interviews revealed some marked differences between normal practise and literature-based prescriptions. An experiment was conducted in which eight practising builders' estimators were separately presented with a representative sample of 36 bill of quantities items taken from groundwork, in-situ concrete work and masonry sections. The estimators stated the method they would normally use to price each item, their 'normal' price rate and their highest/lowest price rate. The results showed that only half the items would be priced by the prescribed 'detailed' method, the remainder being priced mainly by 'experience'. Analysis by work section, item rate, item quantity, item total, item labour content, contribution to the total of the bill, the standard deviation of the inter-estimator intra-item rates and totals, and their coefficients of variation, skewness and kurtosis indicated that the item total was the main factor determining the rating method used, although this varied in importance between work sections. An intra-estimator intra-item analysis of pricing variability generally confirmed the assumption of a constant coefficient of variation.