Term Definition
Sample design
Information on the target and final sample sizes, strata definitions and the sample selection methodology.
Sample element

A selected sampling unit of the target population that may be eligible or ineligible.

Sample management system
A computerized and/or paper-based system used to assign and monitor sample units and record documentation for sample records (e.g., time and outcome of each contact attempt).
Sample person
A person selected from a sampling frame to participate in a particular survey.
Sampling bias
The systematic difference between the expected value (over all conceptual trials) of an unweighted sample estimate and the target population value because some elements on the sampling frame have a higher chance of selection than other elements.
Sampling error
Survey error (variance and bias) due to observing a sample of the population rather than the entire population.
Sampling error computational units (SECUs)

PSUs in ‘one PSU per stratum’ sampling designs that are grouped in pairs, after data collection, for purposes of estimating approximate sampling variances.

Sampling frame
A list or group of materials used to identify all elements (e.g., persons, households, establishments) of a survey population from which the sample will be selected. This list or group of materials can include maps of areas in which the elements can be found, lists of members of a professional association, and registries of addresses or persons.
Sampling units

Elements or clusters of elements considered for selection in some stage of sampling. For a sample with only one stage of selection, the sampling units are the same as the elements. In multi-stage samples (e.g., enumeration areas, then households within selected enumeration areas, and finally adults within selected households), different sampling units exist, while only the last is an element. The term primary sampling units (PSUs) refers to the sampling units chosen in the first stage of selection. The term secondary sampling units (SSUs) refers to sampling units within the PSUs that are chosen in the second stage of selection.

Sampling variance
A measure of how much a statistic varies around its mean (over all conceptual trials) as a result of the sample design only. This measure does not account for other sources of variable error such as coverage and nonresponse.

To answer survey questions optimally, four stages of cognitive processing are required:  (1) interpret the questions comprehensively, (2) retrieve information from memory, (3) form a judgment, and (4) map the judgment to the appropriate response category. However, to lower cognitive burden, instead of seeking to optimize, respondents may skip some steps when the answer survey questions. This behavior is called satisficing.

Satisficing behaviors

Decision-making strategies that entail searching through the available alternatives until an acceptability threshold is met.

Secondary Sampling Unit (SSU)

A cluster of sample elements sampled at the second stage of selection.

Sequential mixed mode
A mixed mode design in which additional modes are offered as part of a nonresponse follow-up program.
Shared Language harmonization

Shared language harmonization can be understood as the procedures and result of trying to harmonize as much as possible different regional varieties of a "shared" language across countries, e.g. in terms of vocabulary and/or structure. An example would be to harmonize translations into Italian between questionnaires used in Italy and in Switzerland.

Silent monitoring

Monitoring without the awareness of the interviewer.

Simple random sampling (SRS)
A procedure where a sample of size n is drawn from a population of size N in such a way that every possible sample of size n has the same probability of being selected.
Social desirability bias
A tendency for respondents to overreport desirable attributes or attitudes and underreport undesirable attributes or attitudes.
Socio-demographic question

A question typically asking about respondent characteristics such as age, marital status, income, employment status, and education.

Example: What year and month were you born?

Soft consistency check
A signal warning that there is an inconsistency between the current response and a previous response. The soft consistency check should provide guidance on resolving the inconsistency, but the interviewer or respondent may continue the survey without resolving it.
Source document
The original document from which other (target) documents are translated or adapted as necessary.
Source instrument
The original instrument from which other (target) instruments are translated or adapted as necessary.
Source language
The language in which a questionnaire is available from which a translation is made. This is usually but not always the language in which the questionnaire was designed.
Source questionnaire

The questionnaire taken as the text for translation. The source questionnaire would normally not be intended to be fielded as such but would require local adaptation even if fielded in the source language: for instance, in the ESS, the source questionnaire is English, but the questionnaires fielded in Ireland and UK differ slightly from the source questionnaire.

Source variables
Original variables chosen as part of the harmonization process.
Split panel

A design that contains a blend of cross-sectional and panel samples at each new wave of data collection.

Split translation

Each translator translates only a part of the total material to be translated in preparation for a review meeting, in contrast to translating the entire text (see full translation).

Stand-alone experiment

An experiment conducted as an independent research project.

Standardized interviewing technique

An interviewing technique in which interviewers are trained to read every question exactly as worded, abstain from interpreting questions or responses, and do not offer much clarification.

Statistical process control chart
A statistical chart that compares expected process performance (e.g., number of hours worked by interviewers in a week) against actual performance. For example, interviewers who perform outside upper and lower boundaries on this measure are flagged; if greater variation from expected performance for some interviewers in a certain location can be explained (e.g., a hurricane or a snow storm causing lower than expected hours worked), the process is in control; if not, corrective actions are taken.
Clicking the same answer for each item in a multi-numeric list.
Strata (stratum)

Mutually exclusive, homogenous groupings of population sample elements or clusters of elements that comprise all of the elements on the sampling frame. The groupings are formed prior to selection of the sample.


A sampling procedure that divides the sampling frame into mutually exclusive and exhaustive groups (or strata) and places each element on the frame into one of the groups. Independent selections are then made from each stratum, one by one, to ensure representation of each subgroup on the frame in the sample.

A technique where each nonresponding sample element from the initial sample is replaced by another element of the target population, typically not an element selected in the initial sample. Substitution increases the nonresponse rate and most likely the nonresponse bias.
Survey lifecycle
The lifecycle of a survey research study, from design to data dissemination.
Survey population
The actual population from which the survey data are collected, given the restrictions from data collection operations.
Survey weight
A statistical adjustment created to compensate for complex survey designs with features including, but not limited to, unequal likelihoods of selection, differences in response rates across key subgroups, and deviations from distributions on critical variables found in the target population from external sources, such as a national Census.
Systematic sampling
A procedure that selects of every kth element on the sampling frame after a random start.