P

Panel Data
A special form of longitudinal data in which observations are collected on the same sample of respondents over a period of time.

Panel Interviewing
Conducting repeated interviews with the same group of respondents over time.

Parameter
A number that describes a population. FOR EXAMPLE, percent of males in the population.

Participant
A resident, family, complex, neighborhood, or community receiving or participating in services provided by the program. Also known as client or target population group.

Participant Observation
A research method involving direct participation of the researcher in the events being studied. The researcher may either reveal or hide the true reason for involvement.

Pearson Product-Moment Correlation Coefficient
A measure of association; a statistic used with interval-ratio variables.

Peer Review
An assessment of a product conducted by a person or persons of similar expertise to the author.

Performance Evaluation
An evaluation that compares actual performance with that planned in terms of both resource utilization and production. It is used by management to redirect program efforts and resources and to redesign the program structure.

Performance Measurement
Involves ongoing data collection to determine if a program is implementing activities and achieving objectives. It measures inputs, outputs, and outcomes over time. In general, pre-post comparisons are used to assess change.

Performance Measures
Ways to objectively measure the degree of success a program has had in achieving its stated objectives, goals, and planned program activities. FOR EXAMPLE, number of clients served, attitude change, and rates of rearrest may all be performance measures.

Pilot
A pretest or trial run of a program, evaluation instrument, or sampling procedure for the purpose of correcting any problems before it is implemented or used on a larger scale.

Pilot Test
Preliminary test or study of the program or evaluation activities to try out procedures and make any needed changes or adjustments. FOR EXAMPLE, an agency may pilot test new data collection instruments that were developed for the evaluation.

Planning
The process of anticipating future occurrences and problems, exploring their probable impact, and detailing policies, goals, objectives, and strategies to solve the problems. This often includes preparing options documents, considering alternatives, and issuing final plans.

Point Biserial Coefficient
A measure of association between an interval-ratio variable and a nominal variable with two attributes.

Point Estimate
An estimate of a population parameter that is a single numerical value. FOR EXAMPLE, the percent of males in the population.

Policy
A governing principle pertaining to goals, objectives, and/or activities. It is a decision on an issue not resolved on the basis of facts and logic only. FOR EXAMPLE, the policy of expediting drug cases in the courts might be adopted as a basis for reducing the average number of days from arraignment to disposition.

Policy Analysis
An analysis used to help managers understand the extent of the problem or need that exists and to set realistic goals and objectives in response to such problem or need. It may be used to compare actual program activities with the program's legally established purposes in order to ensure legal compliance.

Population
The total number of individuals or objects being analyzed or evaluated.

Posttest
A test or measurement taken after services or activities have ended. It is compared with the results of a pretest to show evidence of the effects or changes resulting from the services or activities being evaluated.

Precision
The exactness of a question's wording or the amount of random error in an estimate.

Pretest
A test or measurement taken before services or activities begin. It is compared with the results of a posttest to show evidence of the effects of the services or activities being evaluated. A pretest can be used to obtain baseline data.

Primary Data
Data collected by the researcher specifically for the research project. FOR EXAMPLE, a survey of program participants undertaken by the researcher involves the collection of primary data, while a subsequent review of the program's case files involves the use of secondary data.

Probability Distribution
A distribution of a variable that expresses the probability that particular attributes or ranges of attributes will be, or have been observed.

Probability Sample
A group of cases selected from a population by a random process. Every member of the population has a known, nonzero probability of being selected.

Probability Sampling
A method for drawing a sample from a population such that all possible samples have a known and specified probability of being drawn.

Probe
To examine a subject in an interview in depth, using several questions.

Problem statement
A problem statement should describe the problem, describe its causes, and identify potential approaches or solutions to the problem through the use of literature reviews. In program evaluation, inclusion of a problem statement as part of the model provides an opportunity for the importance of a program to be conveyed. A detailed description of the problem and who is affected can provide a baseline for comparison purposes and a greater understanding of who has benefited from program services.

Process
The programmed, sequenced set of things actually done to carry out a program mission.

Process Evaluation
Process evaluation focuses on how a program was implemented and operates. It identifies the procedures undertaken and the decisions made in developing the program. It describes how the program operates, the services it delivers, and the functions it carries out. Like monitoring evaluation, process evaluation addresses whether the program was implemented and is providing services as intended. However, by additionally documenting the program's development and operation, it allows an assessment of the reasons for successful or unsuccessful performance, and provides information for potential replication.

Productivity
The relationship between production of an output and one, some, or all of the resource inputs used in accomplishing the assigned task. It is measured as a ratio of output per unit of input over time. It is a measure of efficiency and is usually considered as output per person-hour.

Program
A major endeavor authorized and funded to achieve a significant purpose, defined in terms of the principal actions/activities required. It may cross organizational lines.

Program Activities
Activities, services, or functions carried out by the program (i.e., what the program does). FOR EXAMPLE, treatment programs may screen clients at intake, complete placement assessments, provide counseling to clients, etc.

Program Analysis
The analysis of options in relation to goals and objectives, strategies, procedures, and resources by comparing alternatives for proposed and ongoing programs. It embraces the processes involved in program planning and program evaluation.

Program Effectiveness Evaluation
The application of scientific research methods to estimate how much observed results, intended or not, are caused by program activities. Effect is linked to cause by design and analyses that compare observed results with estimates of what might have been observed in the absence of the program.

Program Failure
A program shortcoming in which the outcome criteria are not affected by participation of the subjects in the program (i.e., the program does not accomplish its objective). FOR EXAMPLE, a prison alternative which has no impact on recidivism rates.

Program Implementation Objective
What is planned to be done in the program, components, or services. FOR EXAMPLE, providing security patrols in five buildings three times each evening is a program implementation objective.

Program Justification
The narrative and related analyses and statistical presentations supporting a program budget request. It includes: (1) definitions of program objectives, including a rationale for how the proposed program is expected to help solve the problem and the magnitude of the need, (2) plans for achieving the objectives , and (3) the derivation of the requested appropriation in terms of outputs or workloads showing productivity trends and the distribution of funds among organizational units.

Program Model
A flowchart or model which identifies the objectives and goals of a program, as well as their relationship to program activities intended to achieve these outcomes.

Public Program
Program conducted by a federal, state, or local governmental agency.

Purposive Sample
Instances appropriately selected to answer different evaluation questions, on various systematic bases, such as best or worst practices; a judgmental sample. If conducted systematically, can be widely useful in evaluation.