Research methods/ Threats to experimental validity
1.
2. 1. Internal Validity – refers to the
condition that observed
differences on the dependent
variable are a direct manipulation
of the independent variable
3. 2. External validity – refers to
the condition that applicable
to groups and environments
outside of the experimental
settings
3. Ecological validity – refer to
the degree to which results
can be generalized to other
enviroments
4. •History – refers to the occurrence of any
event that is not part of the experimental
treatment but which may affect
performance on the dependent variable.
5. – refers to physical or
mental changes that may occur
within the subjects over a period of
time.
– refers to improve scores
on a posttest from subjects
having taken the a pretest
6. – refers to
unreliablilty, or lack of
consistency, in measuring
instruments which may result
to invalid assessment of
performance
7. – usually
occurs when the subjects are
selected on the basis of their
extreme score and refers to the
tendency of subjects who score
highest on a pretest to score lower
on a posttest, and of subjects who
score lowest on a pretest to score
higher on a pretest
Threats to internal validity
9. The “etc” means that selection
may also interact with factors
such as history and testing,
although selection- maturation
interaction is more common.
Threats to internal
validity
