In-app programmatic advertising is substantially more prone to fraud and wasted impressions than Web-based ads. This according to a study from Lucidity, which uses a blockchain-based technique to verify ad metrics. While 96% of Web impressions were confirmed by all members of the ad supply chain, just 65% of in-app ads were. Non-confirmed impressions are likely to be fraudulent or wasted. Confirmation rates improved substantially when placements were optimized to avoid discrepancies, which implies (but doesn’t prove) that performance improved as well.