Almost four hundred results of bids for heavy construction contracts are analyzed for correlation between the size of the contract and the difference between the low and second bids. The results of this analysis are applied to four diversified areas of competitive bidding. Namely, another criteria for ascertaining the probable existence of a gross mistake in a bid is offered; a suggested maximum amount of bid guarantee is treated, the practice of using going prices is investigated, and three methods for increasing profits, based on probability factors, are described.