E

Ecological Fallacy
False conclusions made by assuming relationships found through research with groups can be attributed to individuals.

Effect Size
The size of the relationship between two variables (particularly between program variables and outcomes).

Effectiveness
Ability to achieve stated goals or objectives, judged in terms of both output and impact.

Efficiency
The degree to which outputs are achieved in terms of productivity and input (resources allocated). Efficiency is a measure of performance in terms of which management may set objectives and plan schedules and for which staff members may be held accountable.

Empirical
Relying upon or derived from observation or experiment.

Empirical Research
Research that uses data drawn from observation or experience.

Empirical Validity
Empirical evidence that an instrument measures what it has been designed to measure.

Estimation Error
The amount by which an estimate differs from a true value. This error includes the error from all sources (for example, sampling error and measurement error).

Evaluability Assessment
An evaluability assessment is a systematic process used to determine the feasibility of a program evaluation. It also helps determine whether conducting a program evaluation will provide useful information that will help improve the management of a program and its overall performance.

Evaluation
Evaluation has several distinguishing characteristics relating to focus, methodology, and function. Evaluation (1) assesses the effectiveness of an ongoing program in achieving its objectives, (2) relies on the standards of project design to distinguish a program's effects from those of other forces, and (3) aims at program improvement through a modification of current operations.

Evaluation Plan
A written document describing the overall approach or design that will be used to guide an evaluation. It includes what will be done, how it will be done, who will do it, when it will be done, and why the evaluation is being conducted.

Evaluation Practice
A practice or set of practices that consist mainly of management information and data incorporated into regular program management information systems to allow managers to monitor and assess the progress being made in each program toward its goals and objectives. Ideally, a program is self-evaluating, continuously monitoring its own activities.

Evaluation Team
The individuals, such as the evaluation consultant and staff, who participate in planning and conducting the evaluation. Team members assist in developing the evaluation design, developing data collection instruments, collecting data, analyzing data, and writing the report.

Ex-post Facto Design
A research design in which all group selection, pretest data, and posttest data are collected after completion of the treatment. The evaluator is thus not involved in the selection or placement of individuals into comparison or control groups. All evaluation decisions are made retrospectively.

Experimental Data
Data produced by an experimental or quasi-experimental design.

Experimental Design
A research design in which the researcher has control over the selection of participants in the study, and these participants are randomly assigned to treatment and control groups.

Experimental Group
A group of individuals participating in the program activities or receiving the program services being evaluated or studied. Experimental groups (also known as treatment groups) are usually compared to a control or comparison group.

Experimental Mortality
The loss of subjects from an experiment due to such factors as illness, lack of interest, or refusal to participate. This loss may effect the comparability of results between the experimental and control groups.

External Validity
The extent to which a finding applies (or can be generalized) to persons, objects, settings, or times other than those that were the subject of study.

External Validity Threats
Factors that may reduce the transferability of a program's findings to other groups or jurisdictions. FOR EXAMPLE, a program may appear successful using a group of specially selected clients (e.g., first time offenders). However, it would not be a fair test of how this program would work on the general offender population.