Immigration
Movement of people into a country from another country.


In-house recruiting
The recruiting of focus group participants by people who are physically located
within the facility.


Incentive
The payment to participants for coming to a focus group. The amount varies
dramatically, based on the difficulty of recruiting the participants. Also called
honorarium or co-op payment.


Incidence
Any figure referring to the percentage of people in a category. Examples:
incidence of users, incidence of people qualifying for a study.


Income
As defined by the Census Bureau income is wage or salary income;
self-employment income; interest, dividend, or net rental income; Social
Security income; public assistance income; all other income, which includes
unemployment compensation, veterans' payment, pensions, alimony, etc.


Independent samples
Samples in which measurement of a variable in one population has no effect
on the measurement of the variable in the other.


Independent variable
A variable that is controlled or manipulated by the researcher. See also
predictor variables or factor.


Instrument variation
Differences or changes in measurement instruments (e.g., interviews or
observers) that explain differences in measurements.


Intelligent data entry
The logical checking of information being entered into a data entry device by
that machine or one connected to it.


Intercept
A recruitment method in which an interviewer stops people in a mall or other
public location and administers survey.


Internal consistency reliability
Ability to produce similar results using different samples to measure a
phenomenon during the same time period.


Internal database
Database developed from data within the organization.


Internal validity
The extent to which competing explanations for the experimental results
observed can be avoided.


Interrupted time-series design
Research in which the treatment interrupts ongoing repeated measurements.


Intersection
Is the event containing all simple events that are in both event A and event B.
The concept can be extended to more than two events.


Interval
Taking a given number of units equally selected over the full population of
study. The nth number interval is derived by dividing the total number of units
by the sample number desired.  Also known as nth selection.


Interval estimates
Inferences regarding the likelihood that a population value will fall within a
certain range.


Interval scale
Ordinal scale with the additional property that the distance between
observations is meaningful.  An example would be the temperature.  See ratio
scale.


Interviewer
The person responsible for recruiting participants for a focus group or the
person administering a questionnaire.


Interviewer error
Error that results from conscious or unconscious bias in the interviewer's
interaction with the respondent.


Interviewer's instructions
Written directions to the interviewer on how to conduct the interview.


Itemized rating scales
Scales in which the respondent selects an answer from a limited number of
ordered categories.