Chiang, Dana C. Skip to content 5. Explain what external validity is and evaluate studies in terms of their external validity. Explain the concepts of construct and statistical validity.
Key Takeaways Studies are high in internal validity to the extent that the way they are conducted supports the conclusion that the independent variable caused any observed differences in the dependent variable. Experiments are generally high in internal validity because of the manipulation of the independent variable and control of extraneous variables.
Studies are high in external validity to the extent that the result can be generalized to people and situations beyond those actually studied. Judd, C. Estimating the effects of social interventions. Teach your students to be better consumers. APS Observer. Revisiting external validity: Concerns about trolley problems and other sacrificial dilemmas in moral psychology.
The swimsuit becomes you: Sex differences in self-objectification, restrained eating, and math performance. Journal of Personality and Social Psychology, 75 , — A room with a viewpoint: Using social norms to motivate environmental conservation in hotels.
Journal of Consumer Research, 35 , — Previous Section. Next Section. License 5. Fully-functional online survey tool with various question types, logic, randomisation, and reporting for unlimited number of responses and surveys. Internal Validity is the approximate truth about inferences regarding cause-effect or causal relationships.
Thus, internal validity is only relevant in studies that try to establish a causal relationship. But for studies that assess the effects of social programs or interventions, internal validity is perhaps the primary consideration. In those contexts, you would like to be able to conclude that your program or treatment made a difference — it improved test scores or reduced symptomology. But there may be lots of reasons, other than your program, why test scores may improve or symptoms may reduce.
The key question in internal validity is whether observed changes can be attributed to your program or intervention i. There are eight threats to internal validity : history, maturation, instrumentation, testing, selection bias, regression to the mean, social interaction and attrition.
Have a language expert improve your writing. Check your paper for plagiarism in 10 minutes. Do the check. Generate your APA citations for free! APA Citation Generator. Home Knowledge Base Methodology Understanding internal validity.
Understanding internal validity Published on May 1, by Pritha Bhandari. Here's why students love Scribbr's proofreading services Trustpilot.
What is internal validity? What is the difference between internal and external validity? What are threats to internal validity? Is this article helpful? Pritha Bhandari Pritha has an academic background in English, psychology and cognitive neuroscience. As an interdisciplinary researcher, she enjoys writing articles explaining tricky research concepts for students and academics. Other students also liked. The obvious downside to this approach is that it would lower the external validity of the study—in particular, the extent to which the results can be generalized beyond the people actually studied.
For example, it might be unclear whether results obtained with a sample of younger heterosexual women would apply to older homosexual men. In many situations, the advantages of a diverse sample outweigh the reduction in noise achieved by a homogeneous one. The second way that extraneous variables can make it difficult to detect the effect of the independent variable is by becoming confounding variables. A confounding variable is an extraneous variable that differs on average across levels of the independent variable.
But as long as there are participants with lower and higher IQs at each level of the independent variable so that the average IQ is roughly equal, then this variation is probably acceptable and may even be desirable. What would be bad, however, would be for participants at one level of the independent variable to have substantially lower IQs on average and participants at another level to have substantially higher IQs on average. In this case, IQ would be a confounding variable. To confound means to confuse , and this effect is exactly why confounding variables are undesirable.
Because they differ across conditions—just like the independent variable—they provide an alternative explanation for any observed difference in the dependent variable. Figure 6. But if IQ is a confounding variable—with participants in the positive mood condition having higher IQs on average than participants in the negative mood condition—then it is unclear whether it was the positive moods or the higher IQs that caused participants in the first condition to score higher.
One way to avoid confounding variables is by holding extraneous variables constant. For example, one could prevent IQ from becoming a confounding variable by limiting participants only to those with IQs of exactly But this approach is not always desirable for reasons we have already discussed. A second and much more general approach—random assignment to conditions—will be discussed in detail shortly.
Anything that varies in the context of a study other than the independent and dependent variables. When the way an experiment was conducted supports the conclusion that the independent variable caused observed differences in the dependent variable.
These studies provide strong support for causal conclusions. When the way a study is conducted supports generalizing the results to people and situations beyond those actually studied.
The participants and the situation studied are similar to those that the researchers want to generalize to and participants encounter everyday. Skip to content Chapter 6: Experimental Research. Explain what an experiment is and recognize examples of studies that are experiments and studies that are not experiments.
Explain what internal validity is and why experiments are considered to be high in internal validity. Explain what external validity is and evaluate studies in terms of their external validity.
Distinguish between the manipulation of the independent variable and control of extraneous variables and explain the importance of each. Recognize examples of confounding variables and explain how they affect the internal validity of a study. An experiment is a type of empirical study that features the manipulation of an independent variable, the measurement of a dependent variable, and control of extraneous variables.
Studies are high in internal validity to the extent that the way they are conducted supports the conclusion that the independent variable caused any observed differences in the dependent variable. Experiments are generally high in internal validity because of the manipulation of the independent variable and control of extraneous variables.
Studies are high in external validity to the extent that the result can be generalized to people and situations beyond those actually studied.
Practice: List five variables that can be manipulated by the researcher in an experiment. List five variables that cannot be manipulated by the researcher in an experiment.
Practice: For each of the following topics, decide whether that topic could be studied using an experimental research design and explain why or why not. Effect of being clinically depressed on the number of close friendships people have. Effect of paying people to take an IQ test on their performance on that test. Judd, C. Estimating the effects of social interventions. Teach your students to be better consumers.
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