While working on 2015 World Cup Players on my World Championship blog, I added the 128 players from the recent Baku World Cup to the World Championship : Index of players. I started to ask myself a few questions -- How many events does the index of players include? How many players? Which players participated in the most events? -- and so on.
Today I collected the data from that index and loaded it into a database to do some simple queries. I discovered that 803 players have participated in 134 events. A breakdown is shown in the following tables.
The table on the left counts the number of players that participated a certain number of times in World Championship events. For example, one player participated in 22 events and 398 players have participated in a single event. The table on the right shows which players participated in the most events. GM Korchnoi heads the list.
What about those 398 players who have participated in a single event? I count 36 players who appeared only in the 2015 World Cup, and 25 players only in the 2013 World Cup. That's not too surprising, since some of these players will undoubtedly appear in future World Cups.
Somewhat more surprising are the 24 players who participated only in the 2001-02 FIDE Knockout Matches or the 21 players from the 2004 FIDE Knockout Matches. It's increasingly unlikely that any of these players will appear again in a World Championship event.
As for historical tournaments, 11 of the 16 players in the 1851 London Tournament never competed in another event -- there weren't many events at that time. More surprising are the 10 players (out of 24) from the 1964 Amsterdam Interzonal Tournament who never competed again. Why so many from that one tournament?