Here is a really interesting way that transactional data shows other trends. Searching beats CDC.

www.sfgate.com.

Flu Trends, as the product is called, tracks the number of searches by Google's users for flu-related terms like "thermometer" and "cold remedies." A spike in the number of such queries may indicate a flu outbreak in a particular state as people try to find information about their illness. Last year, a test showed that Google's tool highlighted flu outbreaks about two weeks faster than the Centers for Disease Control and Prevention's tracking, which relies on reports from local hospitals and state health departments. Getting a quicker heads-up may allow officials to ensure that there are enough vaccines on hand in a particular area and to warn residents to get their flu shots. "The sooner we have indication that flu is in a community, the earlier public health officials can take action," said Glen Nowak, a CDC spokesman. Google unveiled the product at the start of the flu season, which, according to its data, doesn't seem to have yet had much of an impact on California. Most people who catch the illness recover without much trouble, but it nevertheless manages to kill up to half a million people worldwide annually.