Term Definition
Paradata

Couper first introduced the term “paradata” into survey research methodology field (Groves & Couper, 1998) and the definition of paradata has vastly expanded since then. Paradata now refers to additional data that can be captured during the process of producing a survey statistic (Kreuter, 2013). As discussed in the 2011 International Nonresponse Workshop (Smith, 2011), two main types of paradata are available. One is process paradata, which is collected during the process of data collection, such as time stamps and keystroke data. Another type is related with observational information, such as the observed demographic information of respondents and observed neighborhood conditions.

Pareto chart
A bar chart that reflects the types of most errors in a process, by error type in descending order; for example, the five or six most frequent types of help desk calls from interviewers using computer-assisted interviewing.
Performance measurement analysis
A technique used in quality control to determine whether quality assurance procedures have worked. For example, analysis of routine measures of interviewer or coder performance.
Personally Identifiable Information (PII)

Information that can be used to identify a respondent that minimally includes name, address, telephone number and identification number (such as social security number or driver’s license number), but may include other information including biometric data.

Pilot study

A quantitative miniature version of the survey data collection process that involves all procedures and materials that will be used during data collection. A pilot study is also known as a “dress rehearsal” before the actual data collection begins.

Pledge of confidentiality
An agreement (typically in written or electronic form) to maintain the confidentiality of survey data that is signed by persons who have any form of access to confidential information.
Portable file

A file that is coded in a non-proprietary format such as XML or ASCII and thus can be used by a variety of software and hardware platforms.

Post-survey adjustments
Adjustments to reduce the impact of error on estimates.
Poststratification
A statistical adjustment that assures that sample estimates of totals or percentages (e.g. the estimate of the percentage of men in living in Mexico based on the sample) equal population totals or percentages (e.g. the estimate of the percentage of men living in Mexico based on Census data). The adjustment cells for poststratification are formed in a similar way as strata in sample selection, but variables can be used that were not on the original sampling frame at the time of selection.
Poststratification adjustment
A statistical adjustment that assures that sample estimates of totals or percentages (e.g., the estimate of the percentage of men in living in Mexico based on the sample) equal population totals or percentages (e.g., the estimate of the percentage of men living in Mexico based on Census data). The adjustment cells for poststratification are formed in a similar way as strata in sample selection, but variables can be used that were not on the original sampling frame at the time of selection.
Precision
A measure of how close an estimator is expected to be to the true value of a parameter, which is usually expressed in terms of imprecision and related to the variance of the estimator. Less precision is reflected by a larger variance.
Precoding
When designing the questionnaire and survey instrument, determine coding conventions and formats of survey items (especially the closed-ended questions) based on existing coding frames or prior knowledge of the survey population.
Prescribed behaviors

Interviewer behaviors that must be carried out exactly as specified.

Pretesting
A collection of techniques and activities that allow researchers to evaluate survey questions, questionnaires and/or other survey procedures before data collection begins.
Primacy
Context effects in which the placement of the item at the beginning of a list of response options increases the likelihood that it will be selected by the respondent.
Primary Sampling Unit (PSU)

A cluster of elements sampled at the first stage of selection.

Probability proportional to size (PPS)

A sampling method that assures that sample estimates of totals or percentages (e.g. the estimate of the percentage of men living in Mexico based on the sample) equal population totals or percentages (e.g. the estimate of the percentage of men living in Mexico based on Census data). The adjustment cells for postratification are formed in a similar way as strata in sample selection, but variables can be used that were not on the original sampling frame at the time of selection.

Probability sampling
A sampling method where each element on the sampling frame has a known, non-zero chance of selection.
Process analysis
The use of tools such as flowcharts to analyze processes, e.g., respondent tracking, computerized instrument programming and testing, coding, data entry, etc. The aim is and to identify indicators or measures of the quality of products. Process analysis also is used to identify improvements that can be made to processes.
Process improvement plan
A plan for improving a process, as a result of process analysis. A process improvement plan may result from development of a quality management plan, or as a result of quality assurance or quality control.
Process indicator

An indicator that refers to aspects of data collection (e.g., HPI, refusal rates, etc.).

Processing error
Survey error (variance and bias) that arise during the steps between collecting information from the respondent and having the value used in estimation. Processing errors include all post-collection operations, as well as the printing of questionnaires. Most processing errors occur in data for individual units, although errors can also be introduced in the implementation of systems and estimates. In survey data, processing errors may include errors of transcription, errors of coding, errors of data entry, errors in the assignment of weights, errors in disclosure avoidance, and errors of arithmetic in tabulation.
Progress indicator

An indicator that refers to aspects of reaching the goal (e.g., number of complete interviews).

Proxy interview

An interview with someone (e.g., parent, spouse) other than the person about whom information is being sought. There should be a set of rules specific to each survey that define who can serve as a proxy respondent.

Public use data files

An anonymized data file, stripped of respondent identifiers that is distributed for the public to analyze.

Public-use data file
An anonymized data file, stripped of respondent identifiers that is distributed for the public to analyze.