Its population information system contains the official information for the whole country on the Finnish citizens and aliens residing permanently in Finland.
The fishermen were identified from the Professional Fishermen Register [13], whereas the fishermen's wives and other family members (fishermen's biological children, and biological siblings and their spouses and biological children) were identified from the Population Information System of the Population Register Centre.
Eligible women were drawn from the Population Information System (a national population register) by their birth year.
Cause-of-death statistics are compiled from data obtained from death certificates, which are supplemented with data from the population information system of the Population Register Centre.
The Population Information System, called SIP, a record of the population covered by the VHA that assigns an identification number to each individual, supplied the population denominator.
It is possible that the number of young fathers in the sample is underestimated, because not all of them may be registered in the Population Information System.
Information about the age when the boys had become fathers for the first time was collected from the Finnish Population Information System, which is maintained by the Population Register Center and local register offices.
Addresses of the participants' residences and the global positioning system (GPS) coordinates of these addresses were obtained from the Population Register Center (2000), which maintains the Population Information System in Finland.
The global positioning system (GPS -coordinates of the residential buildinGPS -coordinatesrticipants were ofthened fresidentialulation information system of the Population Register Center using personal identification codes.
All necessary information will be obtained from the electronic information systems of the VHA (see figure 1): (1) The Population Information System (SIP) provides an identification number for each person under VHA coverage, and registers some demographic characteristics, and dates and causes of VHA discharge, including death.
