Recent mergers between traditional and online advertising firms suggest a deep flaw in the advertising business -- a flaw exposed by Google Inc. (NASDAQ: GOOG)'s evidently unstoppable technology edge. How so? While traditional advertisers deliver open-loop systems, Google delivers a closed-loop solution.

The reason that online advertising is growing is because it offers a closed-loop solution -- a notion that I first described in Net Profit. By contrast, TV and newspaper advertising is an open-loop system -- one in which a company pays to reach a viewer without getting any specific feedback on whether the advertising money leads to increased sales.

By contrast, a closed-loop solution measures the specific response to the advertising dollar -- tracking whether a user clicks on an ad and whether that clicking leads to an online purchase. I call it a solution because it lets the advertiser measure the extent to which advertising expense leads to increased sales. The closed-loop solution's ability to measure return on advertising is an enormous breakthrough for advertisers.

As everybody knows, Google's algorithm for linking tiny text advertising to Internet search has boosted the online advertising business. According to the Wall Street Journal [subscription required], those search-related ads now account for 40% of the $20 billion U.S. internet ad market. And internet-ad sales overall have nearly tripled in the past five years -- to 7% of the $286 billion overall U.S. ad market -- up from 3% in 2002.

Moreover, Google's success is coming out of the hide of TV and newspaper advertisers. For example, in 2006 General Motors Corp. (NYSE: GM) cut its TV ad spending 15% to $1.38 billion and reduced its newspaper advertising 60% to $232.1 million. Meanwhile, GM's online spending rose 16% to $130 million.