I

Immediate Outcome
The changes in program participants' knowledge, attitudes, and behavior that occur at certain times during program activities. FOR EXAMPLE, acknowledging gang involvement is an immediate outcome.

Impact
The ultimate effect of the program on the problem or condition that the program or activity was supposed to do something about. FOR EXAMPLE, a 10% reduction in drug activity as a result of increased drug enforcement and investigation. (There also may be unexpected or unintended impacts.)

Impact Evaluation
A type of outcome evaluation that focuses on the broad, long-term impacts or results of program activities. For example, an impact evaluation could show that a decrease in a community's crime rate is the direct result of a program designed to provide community policing.

Implementation
Development of a program. The process of putting all program functions and activities into place.

Implementation Strategy
The plan for development of a program and procedure for ensuring the fulfillment of intended functions or services.

Implemented
Developed or put into place.

Incident-based Crime Files
Data bases or files which maintain information on each offense or incident of crime occurring in a jurisdiction.

Independent Variable
A variable that may, it is believed, predict or cause fluctuation in an dependent variable. FOR EXAMPLE, if it is believed that age influences the frequency of delinquent behavior, age is the independent variable and frequency of delinquent behavior is the dependent variable. In evaluation research, the treatment (or lack of) is typically treated as an independent variable since it is hypothesized that the treatment will influence some subsequent behavior or state.

Index
A set of related measures combined to characterize a more abstract concept.

Index Crimes
Part 1 crimes under the Uniform Crime Reporting System. These include murder and non-negligent manslaughter, forcible rape, robbery, aggravated assault, burglary, larceny-theft, motor vehicle theft, and arson.

Index of Dispersion
A measure of spread; a statistic used especially with nominal variables.

Indicator
A measure that consists of ordered categories arranged in ascending or descending order of desirability.

Indirect Benefit
Results that are related to a program, but not its intended objectives or goals. FOR EXAMPLE, an increase in acceptable caseload per probation officer is due to an increased adherence to probation restrictions arising from a compliance program.

Indirect Costs
The costs associated with impacts or consequences of a program. FOR EXAMPLE, the costs due to reincarceration.

Indirect Impact
An effect of a program that is not associated with one of its stated objectives.

Inferential Statistic
A statistic used to describe a population using information from observations on only a probability sample of cases from the population. FOR EXAMPLE, the average age of a class in high school calculated using a random sample of members of that class.

Informed Consent
A written agreement by the program participants to voluntarily participate in an evaluation or study after having been advised of the purpose of the study, the type of the information being collected, and how information will be used.

Information System
An organized collection, storage, and presentation system of data and other knowledge for decision making, progress reporting, and for planning and evaluation of programs. It can be either manual or computerized, or a combination of both.

In-Person Interviewing
Face-to-face interviewing. The interviewer meets personally with the respondent to conduct the interview.

Input
Organizational units, people, dollars, and other resources actually devoted to the particular program or activity.

Instrument
A tool used to collect and organize information. FOR EXAMPLE, questionnaires, scales, tests.

Instrumental Outcome
A measure or measures of phenomena directly related to program goals and objectives.

Instrumentation Bias
Bias introduced in a study by a change in the measurement instrument during the course of the study. FOR EXAMPLE, the scale loses its calibration over time or a stopwatch slows.

Intermediate Outcome
Results or outcomes of program activities that must occur prior to the final outcome in order to produce the final outcome. FOR EXAMPLE, a prison vocation program must first result in increased employment (intermediate outcome) before it may expect to reduce recidivism (final outcome).

Internal Consistency
The extent to which all items in a scale or test measure the same concept.

Internal Validity
The extent to which the causes of an effect are established by an inquiry.

Internal Resource
An agency's or organization's resources, including staff skills and experience and any information already available through current program activities.

Internal Validity Threat
Factors other than program participation that may affect the results or findings. FOR EXAMPLE, changes in the data collection instrument may influence the findings or a pre-test may influence responses to a post-test.

Interquartile Range
A measure of spread; a statistic used with ordinal, interval, and ratio variables.

Interrater Reliability
The extent to which two different researchers obtain the same result when using the same instrument to measure a concept.

Interrupted Times Series Design
The interrupted time series design involves repeated measurement of an indicator (e.g., reported crime) over time, encompassing periods both prior to and after implementation of a program. The goal of such an analysis is to assess whether the treatment (or program) has "interrupted" or changed a pattern established prior to the program's implementation. However, the impact of alternate historical events may threaten the interpretation of the findings. FOR EXAMPLE, an interruped times series study may collect quarterly arrest rates for drug related offenses in a given community for two years prior to and two years following the implementation of a drug enforcement task force. The analysis focuses on changes in patterns before and after the introduction of the program.

Interval Estimate
General term for an estimate of a population parameter that is a range of numerical values.

Interval Measure
A quantitative measure with equal intervals between categories, but with no absolute zero. FOR EXAMPLE, IQ scores.

Interval Scale
A measurement scale that measures quantitative differences between values of a variable, with equal distances between the values.

Interval Variable
A quantitative variable that attributes of which are ordered and for which the numerical differences between adjacent attributes are interpreted as equal. FOR EXAMPLE, Intelligence scores.

Intervening Variable
A variable that causally links other variables to each other. In a causal model, this intermediate variable must be influenced by one variable in order for a subsequent variable to be influenced. FOR EXAMPLE, it may be expected that a vocational program will change an offender's employment status which will subsequently reduce recidivism. Participation in the vocational program would be the independent variable, employment status - the intervening variable, and rearrest - the dependent variable.

Interviews
Interviews involve face-to-face situations or telephone contacts in which the researcher orally solicits responses.