# Experimental Design Vocabulary

```AP Statistics Experimental Design Vocabulary
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1.
anecdotal data: Data collected from haphazardly selected
individual cases, which often come to attention because they're
striking in some way.
2.
before-and-after design: A special kind of matched-pairs
design, where subjects are matched with themselves, and
responses are measured both before and after a treatment or
event.
4.
5.
20.
block: A division of the subject pool, which is itself divided into
21.
levels: The values of the factors used in the experiment.
22.
lurking variable: A variable that is unobserved but may be the
actual cause of an observed response.
23.
blocking: Dividing the subjects according to a known, influential
24.
census: A collection of data from each and every unit of a
25.
experimental units are assigned at random among all the
treatments.
9.
confounding: A situation that exists when you can't distinguish
between the effects of two or more variables.
10.
control: Accounting for all other potentially influential (lurking)
variables so you can be confident that any differences in the
response variable between groups is due to the explanatory
variable.
11.
control group: A group of experimental units used to account
for potentially influential (lurking) variables so you can be
confident that any differences in the response variable between
groups is due to the explanatory variable.
12.
double blind: A type of design in which both the subjects and
the experimental staff are unaware of the level of the treatment
placebo.
13.
experiment: A method of collecting data in which the
researcher exerts control over the subjects or units in the study.
14.
experimental bias: A design or condition that causes an
experiment to favor certain outcomes over other outcomes.
15.
experimental design: Involves choosing treatments used in an
experiment and describing how subjects or units are to be
assigned to treatments.
16.
experimental units: The individuals on which an experiment
is done.
17.
explanatory variable (independent variable): A variable
that may explain changes in a second variable, or a variable that
contains information that you have.
18.
factors: Another term for the explanatory variables used in an
experiment. The element or elements that may be causing a
particular response.
placebo effect: The tendency of a treatment to fulfill the
expectations of the subjects, not because the treatment is
effective, but because the subjects expect the treatment to work.
26.
population.
8.
observational study: A study that observes individuals and
measures variables of interest, but doesn't attempt to influence
the responses.
variable (such as gender) and replicating the experiment on each
division.
7.
matched pairs: A study design that matches pairs of subjects
(a treated subject and a controlled subject) on characteristics that
are believed to influence the response.
treatment and control.
6.
Hawthorne effect: The tendency of subjects to change their
behavior simply because they know they're being observed.
blind: A type of design in which the subjects are unaware of
whether they received the real treatment or a placebo.
generalizability: The ability of a set of results, or a conclusion,
to be applied to a population of interest.
available data: Data that has been collected in the past,
probably by someone else, and are available for your use.
3.
19.
randomization: The practice of randomly assigning
experimental units to treatment and control groups.
27.
replication: Repeating an experiment on different units or
under different conditions.
28.
response variable (dependent variable): The variable that
shows the value you want to predict.
29.
sample: A subgroup of the group of interest.
30.
secondary data: Another term for available data.
31.
study: A process that gathers and analyzes data.
32.
subject: A human experimental unit.
33.
treatment: The specific experimental condition applied to the
experimental units.
34.
treatment group: A group of experimental units that receives a
treatment for which an effect is being studied.
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