Visitor Counting

There are several reasons to count visitors of a trade show. The most important ones are (1) to facilitate the planning of infrastructural capacities, and (2) to assess the buying power coming to the show, because visitors are representing buying power. Most of the important trade shows count visitors according to rules, imposed by their own associations. These rules define what to count, and how to count. It needs a look to the definitions and processes to understand the visitor numbers reported. Counting concepts are different.

FKM concept counts each paid visit as visitor
In Germany, the country with the highest density of large trade shows, these shows usually count according to FKM-rules. FKM (Gesellschaft zur freiwilligen Kontrolle von Messe- und Ausstellungszahlen, http://fkm.de) was specifically established by German trade show organizers to fix counting rules and audit the organizers applying them. FKM defines a visitor as someone, who is entering the fairground and has a paid ticket or paid voucher. If this person enters x-times the fairground, it will count as x visitors. That way the visits are defined as visitors.
This method is fine to improve the planning of infrastructure, personnel etc. for a proper organization of the show. However, it is somewhat misleading, if it should express the buying power at the show. 

Assessing buying power
If you want to understand the buying power walking around during the days of a show, the reported FKM - number needs to be discounted. Example: Let`s say the trade show reports 100.000 visitors (= entries), and 50.000 of those are from abroad. We know by experience from several trade show statistics that a domestic visitor spends approx. 1,5 days at a large trade show, and a foreign visitor visits approx. 2,5 days this trade show. According to the FKM rules the domestic visitor is counted two times, and the average foreign visitor is counted three times. If you discount accordingly to perceive more correctly the buying power at the trade show, the number of visitors in this example would be 41.667 instead of the reported 100.000.

The example shows that it makes sense to understand how the counting is done. An overview on different concepts of visitor counting at European trade shows has been published in the last Euro Fair Statistics, which can be downloaded here: http://www.uefexpo.ru/_data/objects/57707/fkmStatistics.pdf