Measuring the Quality of the Finnish Population Register with a Survey

Special focus on non-response

Päivi Hokka and Markku NieminenStatistics FinlandSurvey Research Unit

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Structure of the presentation

Aims and design of the Finnish Population Register Quality Study

Methods of investigating non-responseResults of the non-response analysis of 2007

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The Population Register

Contains basic information about Finnish and foreign citizens living permanently in Finland

Information is based on notifications made by private individuals and public authorities

Considered as a high-quality register also at the international level

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Quality Study

Register quality is examined with the help of a survey Idea: to ask people directly, whether the register information on

them is correct or not Conducted by Statistics Finland annually since 1998 Telephone interviews made by statistical interviewers The questions are added to the end of Statistics Finland's

Labour Force Study Sample size 11,000 (persons aged 15 - 74)

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Variables checked in the Quality Study

Permanent addressType of ownership of permanent homeNative languageOccupation

A citizen’s permanent address is the most important The interviewer reads out the address the respondent has

according the Population Register and asks, whether it was the address of his/her permanent home

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Answers to the question concerning permanent address in Quality Study 2007

% NPopulation Register address was respondent’s current address 98.8 9,489

Population Register address was not respondent’s current address 1.2 113

Total 100 9,602

Non-response = 1,205

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Non-response as a challenge

Response rate about 88 – 90 per centSample of 11,000 ——> over 1,000 non-response casesThreat for the credibility of the Quality Study

Since 2003, the validity of the permanent address variable has been intensively inquired for all non-response cases

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The non-response

1) People who can be contacted successfully, but who do not answer the questions

- most of them refuse

2) People who cannot be contacted at all

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Tactics in investigating non-response

The respondent or a substitute

contacted

A short questionabout the permanent

address

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Tactics in investigating non-response

The respondent or a substitute

contacted

No contact

A short questionabout the permanent

address

• Comparison with1) postal address register2) Fonecta Finder

• Visit in the address

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Correctness of addresses of non-response cases in 2007

% N

Population Register address was correct 91.0 1,096

Population Register address was incorrect 4.6 55

Population Register address could not be verified 4.4 54

Total 100 1,205

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Correct addresses among non-response (N=1,096)

27% checked from the respondent or a substitute23% checked with a visit

42% compared with the postal address register7% compared with Fonecta Finder

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Result of the Quality Study 2007 with and without non-response

* When non-response is included, the number of checked cases is 10,753. Missing are the 54 unchecked cases.

% N % NPopulation Register address was respondent’s current address

98.8 9,489 98.4 10,585

Population Register address was not respondent’s current address

1.2 113 1.6 168

Checked cases, total* 100 9,602 100 10,753

Without non-response With non-response

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Number of unresolved cases and share of correct addresses among non-response in 2003 - 2007

0

50

100

150

200

250

2003 2004 2005 2006 2007

Year

Unch

ecke

d ca

ses

(N)

9898,198,298,398,498,598,698,798,898,999

Unchecked cases (N)

Correct address %

Corr

ect

addr

ess

%

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Conclusions

By investigating the non-response cases, as many as 99.5 per cent of the permanent addresses of the sample could be checked

The quality of register information was found to be worse among the non-response cases than the respondents

The reservations in the Quality Study method are linked to the accuracy of the other databases used in comparisons

Intensified inquiries of non-response cases help in approaching the ”truth”