T-distribution
Occurrence often seen with small samples which results in a distribution
similar to the normal distribution but not as peaked.


T-test
Hypothesis test about a single mean if the sample is too small to use the Z-test.


Table of random digits
A table consisting of digits in a completely random order.


Tachistoscope (T-scope)
A device for controlling the intensity and duration of light exposure.
Sometimes used in package testing.


Target population
The population which is being studied.


Telephone areas
Area codes and three-digit prefix calling areas.


Telephone focus groups
A qualitative research methodology in which seven to 10 people are connected
in a telephone conference call and a trained moderator leads them through a
discussion about a particular topic. Basically a focus group that is conducted
via conference calling.


Telephone sample
A group of individuals who are surveyed by telephone.


Television market
The two firms which measure TV audiences, Arbitron and NPD/Nielsen, have
slightly different definitions of television markets(media markets), based on
sampling, etc. Arbitron's TV markets are called Areas of Dominant Influence
(ADIs), while Nielsen's are Designated Market Areas, or DMAs.


Temporal sequence
Appropriate causal order of events.


Temporary population
Temporary residents of an area such as tourists, commuters, snowbirds, etc.


Test market
Trial market for a new product or service offer.


Test statistic
A statistic, calculated from the sample data which is used to test the
hypothesis.


Test-retest reliability
The ability of the same instrument to produce consistent results when used a
second time under conditions as nearly the same as possible.


Testing effect
An effect that is a byproduct of the research process and not the experimental
variable.


Tests of significance
Tests for determining whether observed differences in a sample are sufficiently
large as to be caused by something other than mere chance.


Thematic maps
Computer-generated maps that combine geography with demographic data and
company information on sales, etc.


Theory-construction diary
A journal that documents in detail the thoughts, premises, hypotheses and
revisions in thinking of a humanistic researcher.


Third-person techniques
Ways of learning respondents' feelings by asking them to answer in the third
party; "your neighbour," "most people."


Time series analysis
Any set of data recorded in time intervals. Also called exponential smoothing.


Time use survey
A survey of how people use their time, taken by asking people to record what
they do and how they do it in a diary over several days or weeks.


Topline
Preliminary results from a project, usually showing responses of the total
sample to a few key questions.


Touch tone aided telephone interviewing (TATI)
Interviewer-administered telephone surveying in which the respondent uses the
touch-tone buttons of his or her phone to provide answers.  Also known as
touch tone data entry (TDE).


Touch-tone data entry (TDE)
Interviewer-administered telephone surveying in which the respondent uses the
touch-tone buttons of his or her phone to provide answers.  Also known as
touch-tone aided telephone interviewing (TDE).


Tracking
Studies repeated over time to monitor changes in a brand or product category.


Trade area
Geographical area from which the customers of a business are drawn; it can
be as small as a section of a city or as large as the entire country.


Traffic counters
Machines used to measure vehicular flow over a particular stretch of roadway.


Treatment
The independent variable that is manipulated in the experiment.


Triad
A qualitative research methodology in which a moderator works with three
respondents. Some researchers maintain that the limited number of participants
in a triad permits the moderator to get more information from them than is
possible in a mini-group of full group.


Trial rate
Measures the proportion of people who buy a product at least once.


Trimmed mean
Obtained by trimming a percent of the high and low ends of a distribution and
finding the mean of the remaining distribution.


Triple-S
Emerging standard for the exchange of research data and metadata.


True experimental design
Research using an experimental group and a control group, and assignment of
test units to both groups is randomized.


Two-way focus groups
A target focus group observes another focus group, then discusses what it
learned through observing.


Type I error (A error)
Rejection of a null hypothesis when it is true.


Type II error (B error)
Failing to reject a null hypothesis that is false.