A curious case involving Connells Estate Agents in Leamington Spa has given insight into how local estate agents judge themselves to have sold more properties than any of their competitors - they simply go around and count the "Sold" signs.

Although counting the sold signs in a local area seems laughably simply considering today's technology, it's big business with one analysis company surveying around 85,000 homes every month. A Sunderland company, For Sale Sign Analysis Ltd (FSSA) provide data to estate agents that they have collected by surveying (or visiting) the for sale signs in a local area.

Estate agents have been using this information in their local advertising, and the regulator the Advertising Standards Authority (ASA) has now questioned how reliable this data actually is.

The system came to light after a Leamington Spa agent, Wigwam Independent Ltd, objected to Connells claim of being "TOP selling agent BASED ON A SURVEY COLLECTED ON 15-19 OCTOBER 2005". According to FSSA, Connells were showing "Sold" signs on 16.2% of properties during the survey period, more than any other agent.

The ASA found numerous problems with the data:

• unscrupulous agents could affect the figures by manipulating boards
• agents had different approaches to erecting and removing boards
• agents in a wider area took differing views on local boundaries

After a thorough review, the ASA decided that there were too many discrepancies in the data for it to be a reliable indicator of determining the market leader. Both FSSA and Connells have been warned against using the data when making future advertising claims.