1 1 Kåre Vassenden, Statistics Norway Tbilisi, 6 April 2016 “Methods for linking administrative sources” – the case of Norway Version

Outline of the presentation History The ID-number series used How they are used in the society Linking issues Changes and improvements in the forthcoming new CPR system regarding identification issues 2

Historical background First thoughts of a central population register in Norway probably in 1956 –By Bjørnulf Bendiksen in Statistics Norway (EDP enthusiast, public administration reformer and head of Division for population statistics) The employers’ association asked the Ministry to introduce a standard personal ID-number for reporting of taxes 1960 The Ministry asked Statistics Norway to find a solution 1961 Statistics Norway came up with the PIN, and the CPR as a tool for assigning and management of the number

The two ID-number series in the Population registration system (1) 1. Personal Identification Number (PIN) –Example: –Contains  date of birth  sex  individual number  two check digits –No PIN is reused for another person 4

The two ID-number series in the Population registration system (2) D-number (Dno) –The number as above would be as Dno: –’40’ is added to the day of birth –Created for foreign seamen never staying in Norway. The register was transferred to the Tax Administration in the 1990s and incorporated in the CPR database as a separate table –Until recently, the use was limited mostly to cases involving money –Now more widely used for “never/not yet residents” that need an identity number –Not much more than name and citizenship registered 5

The two ID-number series met in data from the Directorate of Immigration (UDI) 1. Aliens Identification Number (AIN) Assigned to all applicants Example: Person object ID (POID) A technical data base number. Used only in data processing Example: In general: Identification is a bigger challenge for UDI, while at the same time they have been less systematic in the handling of identification issues

The prevalence of the ID-number series in the society PIN –Found in all public administrative registers, and several private ones –A real universal ID-number, used more than ever due to a lot of new IT-systems –People start to remember it and use it as young Dno –Fits into the PIN format, and are found in the PIN field of the administrative registers –The use has increased a lot in particular because of high level of short-term labour immigration AIN –Not really used outside the migration management sector 7

8 The stock of PINs and Dnos in the CPR Counted recently Valid PINs Replaced PINs with reference to the new one without reference to the new one … PINs in total Valid Dnos Replaced Dnos with reference to new Dno with reference to PIN … Dnos in total

Linkage between the CPR and UDB There is a continuous flow of data between the two agencies References to each other ID-number series are stored in both registers However, the quality of the link information is poor for immigrants who arrived 3-4 decades ago UDI has just started to ask for D-numbers to all asylum seekers. Will be automatic in future 9

10 Changes of ID-numbers: Three main types B A 1. Simple change to a new number FF G 2. Duplicate not valid any longer (G) H 3. Change to new number, but no reference to the new one

11 Connection between ID-number series from different agencies B A 1. An ordinary link FF G 2. Two persons in one source are regarded as one in the other

One person may have several ID-numbers 12 ID 1 ID 2 ID 3 ID 4 Person 1. Search for the persons behind the ID-numbers 2. Create link files from ID-numbers series to the persons 3. Assign a unique ID-number to each person. Choice of ID-number series is a practical matter «The person perspective»

13 From links to link file BDA C AD BD CD Link file:

14 Experiences / principles In the processes, distinguish sharply between 1.the issue of person identities and 2.person information 1. Do the necessary ID-work and create a link file –from all replaced and all inferior ID-numbers –to the present and most superior ID-number 2. Use the link file on all input files and match the files and start to analyse the data set DnoPINAIN Inferior…superior

Improving the linkage between the CPR and UDB Duplicates of identity were found in both registers The two “link catalogues” (one in each register) were not identical Statistics Norway used name, sex and date of birth as link key between CPR and UDB data –to repair linkage errors and increase the coverage in old data In case of duplicates: “Lowest common denominator” were used as the principle to define the persons An improved link file from AIN to Dno or PIN was created 15

Summing up: The two main steps illustrated ID-links Different appli- cations of data

17 Possible outcome of the linkage work: Finding the total number of people in relevant Norwegian registers PIN persons UDB Dno register

Looking back and forward The 52-year-old PIN has served the Norwegian society well –It has proved to be a success However, there are needs for changes –The capacity of single dates of birth is low –The dates of birth will catch up with the oldest person in the CPR (born 1854) –A wish to avoid information included in the identifier The Modernisation programme has discussed alternatives –A totally new identifier for everybody is too costly –Sex will be taken out and established as a separate variable –One check digit will loose its function to increase the capacity of the number series The new CPR will handle identity issues in a better way 18

19 Thank you! Kåre Vassenden Statistics Norway Division for population statistics