control and potentially suspect projects. This contrasts with the African roads sample discussed in the introduction, where bids were lower amongst suspect contracts.

**A low ratio of submitted bids to the number of companies that bought bidding documents was considered 30 % or less.** This can be a sign of the low quality of bidding documents, evidence of collusion, or suggest fears of corruption reduced firm interest in bidding. In our dataset, every fifth contract saw a 70 % non-submission rate. The ratio was the same for both potentially suspect and control projects. This matches evidence from the Africa transport sample.

**Foreign companies failing to bid on ICB auctions** may be a sign of restricted competition or firm concerns with regard to corruption.  This red flag appeared twelve times.  Contracts in the potentially suspect group had just one instance of absence of international bidders, a lower ratio than the control group.

**The presence of two almost identical bids was considered to be two bids submitted within a 1% price range.** This might signify potential problems with collusion or one bidder obtaining inside information from a government official. A small gap was revealed in a quarter of all cases. Submission of nearly identical bids occurred at similar rates in the control group and the potentially suspect group.<sup>4</sup>

**A long lag between bid opening and bid evaluation was considered greater than three months.** Longer periods of bid evaluation may allow for negotiation between corrupt bidders and officials to select a particular winner and agree post-award payments (or might merely represent competing priorities, limited capacity or the complexity of negotiations).  In 39 cases from the sample (where relevant information was available), in only 3 instances did we note an extended bid evaluation period.  All of these cases were in the control group.

**A considerable gap between 1st and 2nd bid quotes (in cases where the lowest bidder won) was measured as 30 percent or greater.** As noted above, it is plausible to imagine that a favored company can substantially underbid its competitors in case of advance knowledge of confidential information or bribes that allow it to win with a non-responsive bid.  Out of 40 contracts, for which this information was available, we detected 5 red flags of an unusually wide gap between the winning and the next lowest quote.  Only one of these contracts was in the potentially suspect group.

**That the lowest bidder was considered non-responsive** may in some circumstances be an indication of corruption influencing the selection procedure.  In the study, we drew the conclusion with regard to the red flag of non-responsiveness based on read-out quotes, not on evaluated bids. Overall, in 13 procurement cases out of 60, the lowest (read out)

> 4 Collusion between bidders can also be detected by looking for evidence of obvious similarities between competing bids (e.g. format of bid, identical unit prices, identical spelling, grammatical and/ or arithmetic errors, photocopied documents); bid bonds acquired by competing bidders from the same financial institution; bid bonds with similar dates and/ or sequential serial numbers; bidders propose identical items; and documents from competing firms contain similar or identical company names, handwriting/ signatures, company stationary, invoice numbers, telephone numbers.  However, the aforementioned warnings signs are much more difficult to detect and extract from procurement documents.

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