NIPO ODIN Version 5.17
Stratification (Quota)A stratification file (S-file) is used to divide the sample into several quota groups in which a limited number of interviews must be realized. Stratification is counted on the survey sample, therefore a T-file or Sample table must be provided. Each cell must be defined in one separate record with the following format:
Stratification amounts to storing a property, which is characteristic for a group of respondents, in the stratum field of their telephone records. Each stratum must have a unique characteristic. The characteristics may be stored in the Sample records before the interview program is called (stratification on input) or may be stored by the system during an interview (stratification on output). The characteristic may be formed by a certain value or text. Characteristics containing blanks must be enclosed in quotation marks. A characteristic may occupy 79 positions. The description of a stratum may consist of up to 80 characters. Once a stratification limit is exceeded, the sample records in that stratification cell are blocked (response code 21), which means new interviews cannot take place in that particular stratification cell. When using a T-file blocked sample records will no longer be drawn from the sample, not even after the stratification limit has been changed afterwards. When using a Sample table blocked Sample records will no longer be drawn, but will be released when a stratification limit has been changed by the NIPO Fieldwork System supervisor. When stratification criteria are not known in advance (for instance: age and gender) you cannot check the stratum until after starting the interview, and quiring for the required information first. See the NIPO ODIN commands, Example of a Survey stratification file (T-file) 286 : "N" (100) North Example of a Survey stratification file (Sample file) Region : "N" (100) North The first stratum criterion is Region. The region in this example is stored in position 286 of the sample record (T-file), or in the field When a criterion contains non-numeric characters and / or spaces, it must be embedded in double quotes. The second stratum criterion is Gender. For the T-file, a 1 in position 287 characterizes a Male, and 2 a Female. It's limit is 200 successful interviews each. For the Sample table, the Gender is stored in the first position of the The third criterion is Age Group. For the T-file, it is characterized by value 1 in position 288 for people up to 34, value 2 for people of 35 to 44, value 3 for people of 45 to 54 and value 4 for people of 55 and older. It is the second field in the Finally there is the combined stratum criterion for gender and age. In a T-file, this is stored in consecutive positions 287-288. For the Sample table, these combinations are stored in a single field ( Note: |
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