CD-ROMs for MONICA Monograph and Multimedia Sourcebook

Population survey data component

Contents

• Data-collection procedures
• Data archive format - survey core data
• Data archive format - survey non-respondent data
• Quality of the data
• Data book
• The data

Data-collection procedures

The data-collection procedures for the population survey data component of the WHO MONICA Project are described in the MONICA Manual, Part III, Section 1.

Data archive format - survey core data

The data were transferred from the MONICA Collaborating Centres (MCCs) to the MONICA Data Centre (MDC) using three versions of the Core data transfer format - survey data (Form 04):

• Version 3 - used by all MCCs in the initial survey
• Version 6 - used by most MCCs in the middle survey
• Version 7 - used by all MCCs in the final survey.

In the Basic analysis data set of the MONICA Archive, all survey data are given in a standardised format, which is specified in the Data archive format - survey core data (Form 04, Version 8). The Data archive format includes the data items of all three versions of the Core data transfer format, with the exception that the day of birth is blinded and only the month and year of birth are given. This is done in order to comply with the personal data confidentiality laws of some countries. Furthermore, all years are given in four characters (e.g. 1987 rather than 87), to avoid confusion after the year 2000.

A number of derived data items have been added:

• The version number of the data transfer format in which the data were transferred to the MDC
• Age of the subject on the day of examination
• Age group of the subject on the day of examination
• Identification of 5-year birth cohorts, using two different definitions
• Tertile of years of schooling, using two different definitions
• Systolic and diastolic blood pressure
• Serum total cholesterol (mmol/l)
• HDL cholesterol (mmol/l).

Data archive format - survey non-respondent data

The survey non-respondent data were transferred from the MCCs to the MDC using two versions of the Data transfer format - survey non-respondent data (Form 08):

• Version 2 - used by most MCCs in the initial survey
• Version 3 - used by all MCCs in the middle and final survey.

In the Basic analysis data set of the MONICA Archive, all survey non-respondent data are given in a standardised format, which is specified in the Data archive format - survey non-respondent data (Form 08, Version 4). The Data archive format includes the data items of the two versions of the Data transfer format, with the exception that the day of birth is blinded and only the month and year of birth are given. Also all years are given in four characters (e.g. 1987 rather than 87). A data item for the version number of the data transfer format in which the data were transferred to the MDC has been added at the end of the record.

Quality of the data

The quality of the data, as well as MCC specific characteristics of the data or the data-collection procedures are described in 13 quality assessment reports:

• Assessment of age, date of examination and survey period
• Participation rates, quality of sampling frames and sampling fractions
• Quality assessment of data on marital status and educational achievement
• Quality assessment of data on smoking behaviour
• Quality assessment of data on hypertension control
• Quality assessment of data on awareness and treatment of high cholesterol
• Quality assessment of data on use of aspirin
• Quality assessment of data on menopausal status and hormones
• Quality assessment of blood pressure
• Quality assessment of total cholesterol measurements
• Quality assessment of data on HDL cholesterol
• Quality assessment of weight and height measurements
• Quality assessment of data on waist and hip circumferences

It is important that anyone who intends to analyse the MONICA data is familiar with the relevant quality assessment reports.

Data book

Descriptive statistics calculated from the data as well as commonly used definitions of derived data items can be found in the MONICA population survey data book.

The data

A 20% sample (5% for MCC 39) of the survey core data, in the format specified in the Data archive format - survey core data (Form 04, Version 8), can be found in the files:

• /data/form04_1.txt - for the initial survey (Packed to 682 KB)
• /data/form04_2.txt - for the middle survey (Packed to 587 KB)
• /data/form04_3.txt - for the final survey (Packed to 560 KB).

This sample analysis data set was extracted from the Basic Analysis Data Set of the MONICA Archive using systematic sampling. Tabulations of the distributions of data included in these files are given in document Distributions of the data on form 04 - survey core data.

A 20% sample (5% for MCC 39) of the survey non-respondent data, in the format specified in the Data archive format - survey non-respondent data (Form 08, Version 4), can be found in the files:

• /data/form08_1.txt - for the initial survey (Packed to 55 KB)
• /data/form08_2.txt - for the middle survey (Packed to 52 KB)
• /data/form08_3.txt - for the final survey (Packed to 56 KB).

This sample analysis data set was extracted from the Basic Analysis Data Set of the MONICA Archive using systematic sampling. Tabulations of the distributions of data included in these files are given in document Distributions of the data on form 08 - survey non-respondent data.

The MONICA Reporting Units and surveys included in the data files are those specified in Table 1 of the  report "Age, date of examination and survey periods in the MONICA surveys".