II - Introduction to Simple Experiments Flashcards
Condition
One of the levels of the independent variable in an experiment
(design) Confound
Think order effects…. fatigue. that is a confound. another variable..?
systematic variability
In an experiment, the
situation that occurs when the levels of a
variable coincide in some predictable way with
experimental group membership, creating a
potential confound
unsystematic variability
In an experiment, the
levels of a variable occurring independently of
experi t l g b hi t ib ti g imental group membership, contributing
to variability within groups.
selection effect
A threat to internal validity that
occurs when the kinds of participants at one
level of the independent variable are
systematically different from those at the other
level of the independent variable
random assignment
The use of a random
method (e.g., flipping a coin) to assign
participants into different experimental groups.
matched-groups design
An experimental
design in which participants who are similar on
some measured variable are grouped into sets
and the members of each matched set are
then randomly assigned to different
experimental conditions.
between-subjects design
An experimental design in which different
groups of participants are exposed to different
l l f th i d d t i bl h th t h levels of the independent variable such that each
participant experiences only one level of the
independent variable independent variable.
within-subjects design
A
study des g c eac pa t c pa t s design in which each participant is
presented with all levels of the independent
variable.
posttest-only design
An experiment with an
independent-groups design in which
participants are tested on the dependent
variable only once.
pretest/posttest design
An experiment with an
id dnepenent-groups d i i hi h design in which
participants are tested on the key dependent
vari bl ae twi ce; once b f d f before and once after
exposure to the independent variable
partial-counterbalancing
A method of
counterbalancing in which some, but not all, of
the possible condition orders are represented.
Latin square:
A formal system of partial
counterbalancing that ensures that each
condition appears in each position at least
once.
carryover effect:
A type of order effect that
occurs when being exposed to one condition
changes how people react to a later condition.
Practice effect
A type of order effect in which people s performance improves over time 's performance improves over time because they become practiced at the dependent measure (not because of the manipulation or treatment).
