Weighting overview

In the Standard and special topic Eurobarometer series and  starting with survey 32, for each of the participating countries a comparison between the sample and a proper universe description is carried out for internal weighting purposes. For an evaluation of this post-stratification weighting (also refered to as redressment or non-response weighting) in the Eurobarometer context see: Sabine Häder and Siegfried Gabler: Deviations from the Population and Optimal Weights, in: ZUMA Nachrichten Spezial. Band 2. For variable labelling and description see the paragraph on "SAMPLE/NATION WEIGHTS". 

The universe description is made available by the National Research Institutes and/or by EUROSTAT. On this basis a national weighting procedure, using marginal and intercellular weighting, is applied. As such in all countries, minimum sex, age, region NUTS II (basic regions as defined by the EUROSTAT nomenclature of territorial units for statistics), and size of locality are introduced in the iteration procedure.

A design weight adjusting for unequal selection probabilities is not available for the Eurobarometer series.

The population size weighting factor corrects for the fact that most countries have almost identical sample sizes, no matter how large or small their populations are. These weights ensure that each country as well as the lower level samples (Northern Ireland, East and West Germany) are represented in proportion to its population size within different country groupings or the respective country (United Kingdom, Germany). The population size weights include the post-stratification weighting factors. For variable labelling and description see the paragraph on "EU WEIGHTS". 

Up to six SAMPLE/NATION WEIGHTS are provided for use in separate analysis of individual countries. The following description refers to Eurobarometer 32 (Autumn 1989) and the following. In the case of former Eurobarometer national weighting factors have not been provided continuously for all countries and the weighting procedure might differ from the foregoing description. For information on available weighting factors in former surveys up to Eurobarometer 31 please see the attached weighting overview (115 KB) and the individual description in the respective codebooks. Please notice that starting with Eurobarometer 54.2 the weighting factors (as described below) are not any more adjusting the samples to their respective standard sizes. This is supposed to have no consequence for the data analysis.

• WEIGHT RESULT FROM TARGET (W1) reproduces the real number of cases for each country. British and Northern Irish as well as East and West German samples are weighted separately. This weight is available starting with survey 34 and corresponds in its function to former NATION WEIGHT II (as available until Eurobarometer 31A). This weight assumes that all samples are analyzed separately.
  

• WEIGHT ADJUSTED TO STANDARD SIZE is equivalent to WEIGHT RESULT FROM TARGET but adjusting all samples to the standard size of 1000 cases (respectively 300 for Northern Ireland and 500/600 for Luxembourg). For surveys 32 and 33 the 'United Kingdom' weighting factor is included. This weight is usually applied in the reports produced on behalf of the European Commission if samples are analyzed separately. This weighting factor is only available up to survey 54.1.

• WEIGHT SPECIAL GERMANY (W3) adjusts the East and the West German samples to their respective proportions in the united Germany. All national weightin factors are included and all samples are adjusted to the standard size. This weight has to be applied whenever the united Germany (East+ West) is analyzed as a whole. This weight is available starting with Eurobarometer 34. Until survey 54.1 the samples are adjusted to the standard size. Starting with Eurobarometer 62 all other samples are excluded from calculation. 

• WEIGHT SPECIAL UNITED KINGDOM (W4) adjusts the British and the Northern Irish samples to their respective proportions in the United Kingdom and has to be applied whenever the United Kingdom is analyzed as a whole. All national weighting factors are included. Unlike the corresponding former NATION WEIGHT I (as available until Eurobarometer 31A) all samples up to survey 54.1 are adjusted to the standard size. Starting with Eurobarometer 62 all other samples are excluded from calculation. 
  

• WEIGHT SPECIAL UNITED KINGDOM + GERMANY combines the special weighting factors for the United Kingdom and the united Germany (East+ West) for simultaneous analysis of both. This combined weight is available from Eurobarometer 47 to 61.   
  

• Separate weights are available for the autonomous participants like Finland (before becoming official member) or Norway: WEIGHT RESULT FROM TARGET FINLAND ONLY contains weights that adjust the weighted sample to enhance the representative for Finland. The real number of cases is reproduced. WEIGHT RESULT FROM TARGET NORWAY ONLY contains weights that adjust the weighted sample to enhance the representative for Norway. The real number of cases is reproduced.

The EU WEIGHTS include the adjustments of each national sample in proportion to its share in the total population of the European Union (European Community), aged 15 and over. These adjustments are based on population figures published by EUROSTAT in the Regional Statistics Yearbook. The EUROPEAN WEIGHTs include the post-stratification sample weighting factors. Up to 22 European weights are provided for use in analyses of the European Union population as a whole or in accordance with its historical compositions. Unlike the former EUROPEAN WEIGHT (as available until Eurobarometer 31A) the total of samples is adjusted to the standard size up to survey 54.1. In general all samples which are not relevant (i.e. not belonging to the respective group of samples) are excluded from calculation.

• WEIGHT EU 6 (W5)  refers to the group of the six EC founder members France, Belgium, Netherlands, West Germany, Italy, and Luxembourg.

• WEIGHT EU 9 (W6)  adds the thre new members as of 1973: Denmark, Ireland and the United Kingdom (Great Britain+Northern Ireland).   

• WEIGHT EU 10 (W7) adds Greece (enlargement 1975).  

• WEIGHT EU 12 (W8) refers to the group of twelve member countries after the 1986 enlargement (Spain and Portugal); after the re-unification of Germany EU WEIGHT 12+ (W9) adds East Germany starting with a separat sample in 1990 (Eurobarometer 34).

• WEIGHT EU 15 (W11) in addition includes the new member states (NMS) as of the 1995 enlargement. WEIGHT EU NMS3 (W10) adjusts the populations of the three new members Austria, Sweden and Finland. 

• WEIGHT EU 25 (W14) refers to the group of  the 25 EU member countries after the 2004 enlargement; WEIGHT EU NMS10 (W13) adjusts the populations of the ten new member countries  Cyprus (Republic), Czech Republic, Estonia, Hungary, Latvia, Lithuania, Malta, Poland, Slovakia and Slovenia.

• WEIGHT EU 27 (W22) adds the the two accession countries Bulgaria and Romania as of 2007; WEIGHT EU NMS12 (W24) adjusts the populations of the therewith in total 12 eastern enlargement member countries; WEIGHT ACCESSION COUNTRIES (W18) reduces the calculation to the group of these two accession countries (AC).  

• WEIGHT EU 29 (W16) in addition includes the remaining two candidate countries as of 2007, Turkey and Croatia; WEIGHT CANDIDATE COUNTRIES (W19) reduces the calculation to the group of these two candidate countries (CC); WEIGHT AC/CC (W15) adjusts the populations of the four accession and candidate countries as a group.     

• Particular EUROPEAN WEIGHTS may include one or more additional countries which are intermittently surveyed in recent Eurobarometers: Macedonia, the Turkish Cypriote Community (TCC) or any of the EFTA countries, as indicated in each case. 

• WEIGHT TOTAL (WEIGHT EUROPE + total n of participating countries) adjusts the populations of ALL participating samples as a group. This weight should only be applied all participating countries (=samples) are to be analyzed in total.     

• WEIGHT SPECIAL EURO ZONE separates the group of eleven countries which accepted to introduce the EURO (Common European Currency), as of 1999 (Belgium, Germany, Spain, France, Ireland, Italy, Luxembourg, the Netherlands, Austria, Portugal and Finland) from the non-EURO countries (EB 49 to 59.1). Starting with Eurobarometer 54.0 an (additional) EURO ZONE weight includes Greece in the group of countries which adopted the EURO as of 2001. WEIGHT SPECIAL EURO ZONE 13 adds Slovenia (2007), WEIGHT SPECIAL EURO ZONE 16 (W81) in addition covers Cyprus (Republic), Malta and Slovakia (2008/2009).

• WEIGHT SPECIAL NON-EURO ZONE reduces the calculation to the group of the respective non-EURO, but EU member countries.

• WEIGHT EFTA (W17) refers to the group of the three EFTA countries Iceland, Norway and Switzerland, if available in the particular survey.
    

OVERSAMPLES are weighted separately as documented in the respective codebooks / variabale description or in the technical specifications.

WEIGHT EXTRA POPULATION 15+ extrapolates the actual universe (population aged 15 or more) for each country/sample, i.e. this weight variable integrates all other available weights, but does not reproduce the number of cases in the data set, but projects the survey results onto universe figures. This weight is available from Eurobarometer 66.2 onwards.

© GESIS Meinhard Moschner