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An Introduction to Panel Surveys in Transportation Studies


ADJUSTED WEIGHTS: See nonresponse weighting.

CALIBRATION EXPERIMENT: When old and new versions of a survey instrument are administered to different portions of the sample to assess the impact of changes in the questions on responses.

COHORT: A group of individuals within a population who have experienced the same life event during some specified period in time. Cohort is usually defined by year or period of birth, but it may be used to refer to the timing of any number of other life events, such as year of retirement or year of marriage.

CONDITIONING: See time-in-sample effects.

CPS: Current Population Survey.

DNMP: Dutch National Mobility Panel.

FIELD PERIOD: The time period during which survey data are collected from the respondents.

HOUSEHOLD: The U. S. Bureau of the Census defines a household as all persons who occupy the same housing unit. A household may consist of a family, one person living alone, two or more families living together, or any other group of related or unrelated persons who share living arrangements.

HOUSING UNIT: The U. S. Bureau of the Census defines a housing unit as a house, apartment, mobile home, group of rooms, or single room that is occupied (or if vacant, is intended for occupancy) as separate living quarters. To qualify as a housing unit, the occupants must live and eat separately from any other persons in the building and have direct access from the outside of the building or through a common hall.

INCENTIVE: A monetary or nonmonetary gift or payment offered to sample members in an effort to gain their cooperation.

LOCATING LETTER: A letter sent by mail to the respondents in advance of the next data collection period in an effort to obtain updated addresses and telephone numbers before the next round of data collection.

LONGITUDINAL WEIGHTS: Weights designed to be used in longitudinal analyses of data from a panel survey.

LONGITUDINAL PANEL DESIGNS: Designs that collect information on the same set of variables from the same sample members at two or more points in time.

MODULE: An independent part of a questionnaire that covers a single subject or topic of interest.

NLSY: National Longitudinal Survey of Youth.

NMES: National Medical Expenditure Survey.

NONRESPONSE: Failure of the survey to obtain the desired information from eligible sample members.

NONRESPONSE WEIGHTING: Postsampling statistical adjustment to partially compensate for possible nonresponse error. Statistical weighting to compensate for nonresponse is different from the postsampling weighting that is routinely performed to adjust for unequal probabilities of selection.

ONE-TIME CROSS-SECTIONAL DESIGNS: Designs in which sample members are asked to complete a survey once.

PANEL ATTRITION: Failure of first-wave respondents to complete the survey in subsequent rounds of a panel survey.

PANEL DESIGNS: Designs that collect repeated measurements on the same sample of individuals or households over time.

PANEL FATIGUE: See time-in-sample effects.

POST-STRATIFICATION: When weights are adjusted to agree with independent population estimates. Post-stratification compensates for deviations between the distribution of characteristics in the sample and the target population.

PSTP: Puget Sound Transportation Panel.

REPEATED CROSS-SECTIONAL DESIGN: Designs that collect measurements on a population over time by repeating the same survey on two or more occasions. During each time period, a separate but comparable sample of units is drawn from the population.

RESPONSE RATE: A measure of a survey's level of success in obtaining the desired measurements from all eligible units in the sample; the number of respondents divided by the total number of eligible units in the sample.

RETENTION RATES: The proportion of respondents from the first wave who complete later waves of data collection in a panel survey.

ROTATION GROUP BIAS: See time-in-sample effects.

ROTATING PANEL DESIGNS (REVOLVING): A panel design that collects measurements on a sample for some specified number of periods after which the sample is dropped from the survey and replaced with a new but comparable sample of units drawn from the current population.

ROTATION GROUP: A sample of units drawn from the population at the same time and following the same schedule of data collection in a rotating panel design.

RDD: Random Digit Dialing. Techniques that form samples by adding random digits to the telephone prefixes that fall within the sampling area so as to include both listed (published) and unlisted numbers in the sample.

SAQ: Self-administered questionnaire. A questionnaire that is completed by the sample member without the assistance of an interviewer. Respondents to self-administered questionnaires are asked to read the questions and record the answers on their own.

SAMPLING UNIT: An element in a sampling frame from which a survey sample is drawn.

SEAM EFFECTS: Apparent increase in the number of changes across rounds of a survey as compared to the number observed within a round.

TIME SERIES DESIGN: A design that collects a series of repeated measurements over a relatively large number of points in time.

TIME-IN-SAMPLE EFFECTS: Effects of prior reporting on reporting in subsequent waves of data collection. Conditioning and fatigue refer to reduced levels of reporting across waves. Rotation bias refers to differences across rotation groups related to their time in the sample.

WAVE: A distinct occasion when data are collected in a panel survey. Also referred to as a round of data collection.

WEIGHTED RESPONSE RATE: A response rate that is calculated using the inverse of the selection probabilities as the weight. The weighted response rate is an estimate of the proportion of the target population represented by the respondents to the survey.

Updated: 3/25/2014
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