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Random Digit Dialling
Random Digit Dialling, commonly known as RDD, is a highly cost effective method of generating a representative sample of households with fixed line telephones. It is particularly useful when there are no requirements for targeting within specific population segments (for example, by gender, income or precise geographic location), or in countries where there is no other sample source readily available.
The actual procedures for RDD are complex, and involve far more than just dialling numbers at random. Two main methods are used: pure RDD, which builds blocks of numbers from information provided by the regulatory bodies, and representative RDD, which builds from seed numbers selected from directories.
In many countries, it is also possible to pulse selected numbers by sending a momentary signal to identify whether it is a live number. Although not 100% effective this procedure significantly improves the productivity of the sample.
Sample Answers have been leading providers of RDD sample for many years, and have constantly refined our procedures to maximise the productivity of RDD sample provided to our clients throughout the world. Below is a list of the countries that we have supplied landline RDD for:
- Australia
- Belgium
- Brazil
- Canada
- Czech Republic
- Denmark
- Dominican Republic
- Netherlands
- France
- Germany
- Greece
- Hungary
- India
- Indonesia
- Republic of Ireland
- Italy
- Japan
- South Korea
- Malaysia
- Mexcio
- New Zealand
- Poland
- Russia
- Singapore
- Slovakia
- South Africa
- South Korea
- Spain
- Sweden
- Switzerland
- Taiwan
- Turkey
- UK
- USA
NB. In some countries the geographic distribution of numbers selected by RDD will not be representative of the population distribution, depending on the local telephone networks.
Sample Answers also provides RDD for mobile / cell phones, again a list of the countries that we have supplied this product for is provided below:
- Australia
- Brazil
- Canada
- China
- Czech Republic
- Denmark
- Dominican Republic
- Finland
- France
- Germany
- Italy
- Japan
- Mexico
- New Zealand
- Poland
- Portugal
- Republic of Ireland
- Russia
- South Korea
- Spain
- Sweden
- UK