Why do some areas win more than others?

Only eircodes entered into the draw (and verified) can win.  

Each eircode entry has the exact same chance of being selected in a draw. 

If one eircode is entered more than once it is more likely to be selected (like names in a hat). 

If a certain eircode area appears to not win often that is because there aren't many entries for that area.  If an eircode area seems to win more often it must mean that there are more entries from that postcode area.

You should find the ratio between entries and winners is roughly the same for different postcodes/areas.

There is no geographical bias in the selection procedure. The computer doesn't know (or care) where you live!