World Values Survey Official Aggregate 1981-2008

Detailed sample guidlines for each Round as well as each country can be obtained from here:

http://www.wvsevsdb.com/wvs/WVSTechnical.jsp?Idioma=I

General Guidlines:

The preferred method of sampling for WVS surveys is the full probability sample. However, recognizing that the very high cost -in terms of finances, manpower and time- of full probability samples may prove to be prohibitive in some cases, WVS allows quota sampling provided that the following principles are strictly adhered to:

1. Selection of PSUs must be probabilistic (and preferably PPS).

2. Selection of first stage clusters within PSUs must be probabilistic (and preferably PPS).

3. Quota sampling should be used only within reasonably small sized clusters that have been selected probabilistically.

Whether the sampling method is full probability or a combination of probability and quota, the minimum number of PSUs is 30. A design with less than 30 PSUs is not permissible.

B. SAMPLE SIZE
The minimum sample size (i.e. the number of completed interviews) is 1,000. However, given the fact that in most designs the "effective sample size" (sample size net of design effects) is lower than the actual sample size, larger sample sizes are strongly recommended if at all possible.

C. NON-RESPONSE
Non-response is an issue of increasing concern in sample surveys. Investigators are expected to make every reasonable effort to minimize non-response.

More specifically,

1. In countries using a full probability design, no replacements are allowed. PIs should plan on as many call-backs as the funding will allow.
2. In countries using some form of quota sampling, every effort should be made to interview the first contact. In any case, and as indicated below, a full report on non-responses is required.