What are the threats to internal and external validity?
Threats to internal validity may be a source of extraneous variance when the findings are not significant. External validity is addressed by delineating inclusion and exclusion criteria, describing subjects in terms of relevant variables, and assessing generalizability.
What are threats to internal validity?
There are eight threats to internal validity: history, maturation, instrumentation, testing, selection bias, regression to the mean, social interaction and attrition.
What are threats to external validity?
There are seven threats to external validity: selection bias, history, experimenter effect, Hawthorne effect, testing effect, aptitude-treatment and situation effect.
When is external validity a threat to internal validity?
Threats to internal validity may be a source of extraneous variance when the findings are not significant. External validity is addressed by delineating inclusion and exclusion criteria, describing subjects in terms of relevant variables, and assessing generalizability.
What are the threats to the validity of research?
Two classes of factors that jeopardize the validity of research findings • Factors concerned with internal validity. – Do the research conditions warrant the conclusions? – Without internal validity results are uninterpretable.
How is Resentful demoralization a threat to internal validity?
Resentful demoralization of respondents receiving less desirable treatments: Again, if desirable services are not provided to those in the control/comparison group, rather than compensating they may become unmotivated or less cooperative. Below are examples of health program evaluations, each highlighting a specific threat to internal validity.
What are the factors that affect internal validity?
Factors affecting Internal Validity Internal validity is threatened whenever there exists the possibility of un- controlled extraneous variables that might otherwise account for the results of a study. Eight classes of extraneous variables can be identified.