Race
As defined by the U.S. Census Bureau: Aleut, American Indian, Asian, Black
(or Negro), Chinese, Eskimo, Filipino, Guamanian, Hawaiian, Japanese,
Korean, Samoan, Vietnamese, White, or "other."


Random
Being or relating to a set or element in which each set or element has an equal
(non-zero) probability of occurring.


Random error
Error that affects measurement in a transient, inconsistent manner.


Random sampling
A sample in which each unit has an equal and independent chance of selection.
Also known as probability sample.


Random variable
A variable whose value is determined by the outcome of an experiment in
which the outcome is subject to chance.  For example "heads" or "tails"  is a
random variable for a coin toss.


Random-digit dialling
A telephone sampling procedure that generates random combinations of
telephone numbers in order to include unlisted numbers in a survey sample.


Randomization
The random assignment of subjects or treatment conditions to ensure equal
representation of subject characteristics in all groups.


Range
The highest value for a variable minus the lowest value for that variable.


Rank-order scales
Scales in which the respondent compares one item with another or a group of
items against each other and ranks them.


Rate
A fixed ratio between two things.


Ratio
A measure that expresses the relative size of two numbers.


Ratio scale
Identifies categories of the variable in which observations can be ranked from
smallest to largest and the distance between variables is meaningful and the
ratios of the observations are meaningful.  The ratio scale is for variables that
have a uniquely defined zero. Examples include weight, height, age, etc.


Recommendations
The section of the final report that suggests the next action steps a client could
take, based on the conclusions of the research.


Recruitment
The process of securing participants for focus groups.


Regression analysis
A multivariate technique that relates a dependent variable to one or more
independent variables.


Regression coefficients
Values that indicate the effect of the individual independent variables on the
dependent variable.


Regression to the mean
Tendency for behaviour of subjects to move toward the average for that
behaviour during the course of an experiment.


Rejection region
Those values of the test statistic that would lead to the rejection of the null
hypothesis.


Related samples
Samples in which the measurement of a variable in one population may
influence the measurement of the variable in the other.


Reliability
Measures that are consistent from one administration to the next.


Repeat rate
The proportion of first-time users of a product who purchase the product at
least a second time.


Repeat-pairs technique
A product testing procedure in which respondents express a preference between
two products, then repeat the task with an identical pair of products.


Replicate
Geographically representative subsample which is systematically selected from
the entire sample.


Representative sample
A sample in which each unit has an equal and independent chance of selection.
Also known as probability sample or random sampling.


Re-screening
A brief interview conducted with potential participants when they arrive at a
facility to ensure that they really qualify for the session. Re-screening normally
uses some of the questions that were originally asked when the participants
were originally recruited.


Research design
The plan to be followed to answer the research objectives; the structure or
framework to solve a specific problem.


Residual error
What still cannot be explained, after estimating the coefficients of the
independent variables. Usually blamed on measurement or omissions.


Respondent
The individual from which data are collected. Also called participant, unit, unit
of analysis, subject or experimental unit.


Response bias
Error that results from the tendency of people to answer a question falsely,
through deliberate misrepresentation or unconscious falsification.


Rule
A guide or a command that tells a researcher what to do.


Rustbelt
States in the Great Lakes region.