Chong-ho Yu (2021) Show
The books by Campbell and Stanley (1963), Cook and Campbell (1979), and Shadish, Cook, and Campbell, (2002) are considered seminal works in the field of experimental design. The following write-up is based upon their books with insertion of my examples and updated information. Problem and Background
Factors Jeopardizing Internal and External ValidityPlease note that validity discussed here is in the context of experimental design, not in the context of measurement. Three Experimental DesignsTo make things easier, the following will act as representations within particular designs: Three True Experimental DesignsThe next three designs discussed are the most strongly recommended designs: Discussion on causal inference and generalizationAs illustrated above, Cook and Campbell devoted much efforts to avoid/reduce the threats against internal validity (cause and effect) and external validity (generalization). However, some widespread concepts may also contribute other types of threats against internal and external validity. Reference
What are the threats to internal validity of an experiment?There are eight threats to internal validity: history, maturation, instrumentation, testing, selection bias, regression to the mean, social interaction and attrition.
What are the 4 threats to internal validity?History, maturation, selection, mortality and interaction of selection and the experimental variable are all threats to the internal validity of this design.
Which threat to internal validity refers to subjects dropping out of a study before it is completed?Participants frequently drop out of experiments whilst they are taking place/before they finish; something that is known as experimental mortality (or experimental attrition).
What does threats to internal validity mean?Single group threats to internal validity refer to threats that can arise when your study treatment focuses on one group. This refers to the criticism or confusing variable that can arise when your research focuses on one sample group.
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