From the article: Log analysers are not accurate. They over-report visits and over-count some browsers while under-counting other browsers. They cannot accurate

From the article: Log analysers are not accurate. They over-report visits and over-count some browsers while under-counting other browsers. They cannot accurately distinguish spiders and robots from human visitors and they do not use fool-proof techniques for counting visits and visitors. Would you use the program that tells you that you've had 1 million users or 100 million users? Even if you're objective, the market is skewed by those who are less objective.