Neural network
A computer program that mimics the function of the human brain. In
marketing research, neural networks are used as data analysis tools. By
harnessing a computer's ability to process millions of calculations quickly,
neural networks can identify patterns, draw abstractions and uncover
relationships in large amounts of data.


Nixie
Mailing piece returned to mailer by the Postal Service because of an incorrect
or undeliverable name or address. The nixie rate varies widely depending on
the source of the mailing list.


No-show
A focus group participant who agrees to come to a session and is confirmed
the same day, but nonetheless does not come to the group. Facilities
compensate for no-shows by over-recruiting for groups by two or three people.


Nominal grouping session
Qualitative research method in which consumers, brought together in small
groups, independently generate ideas about a subject and hence discuss the
ideas.


Nominal scale
Identifies categories of the variable.  Categories are called classes or levels.
Examples: male/female, user/nonuser.


Non-family household
A household comprised of a person living alone or with non-relatives, as
defined by the Census Bureau.


Non-random
Occurrences which do not have an equal probability of occurring; not
mathematically predictable on the basis of the classical theory of probability.


Non-balanced scales
Scales weighted toward one end or the other.


Non-comparative
A judgment made without reference to another object, concept, or person.


Non-probability sample
Subset of a population in which little or no attempt is made to ensure a
representative cross section.


Non-response bias
Error that results from a systematic difference between those who do and do
not respond to the measurement instrument.


Non-sampling error
All the sources of bias or inaccuracy in a study besides sampling error.
Examples: leading by the interviewer, recording/data entry errors.


Normal distribution
A continuous distribution that is bell shaped and symmetrical about the mean.


Nth selection
Statistical means of taking a given number of names or 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 interval.


Null hypothesis
The statement being tested in a test of significance.


Numeric database
Database containing original survey data on a wide variety of topics.