Internal Validity
Internal validity indicates the degree to which an empirical study's design justifies the conclusion that changes in the independent variable directly caused the observed differences in the dependent variable. Experimental research designs typically achieve high internal validity because they involve deliberately manipulating an independent variable while rigorously controlling for extraneous variables, thereby eliminating alternative causal explanations. For instance, in the Darley and Latané experiment, the rigorous manipulation of the number of perceived bystanders isolated this independent variable as the direct cause of differences in helping behavior. In contrast, non-experimental correlational designs exhibit low internal validity; for example, a statistical relationship between regular exercise and happiness cannot confirm that exercise causes happiness, as other factors or reverse causation might explain the link.
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References
Clinical Psychology Eighth Edition
KPU Research Methods in Psychology - 4th American Edition
KPU Research Methods in Psychology - 4th American Edition
KPU Research Methods in Psychology - 4th American Edition
KPU Research Methods in Psychology - 4th American Edition
KPU Research Methods in Psychology - 4th American Edition
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Clinical Practice of Psychology
Psychology
Social Science
Empirical Science
Science
KPU
Research Methods in Psychology - 4th American Edition @ KPU
OpenStax Psychology (2nd ed.) Textbook
Related
Within-Group Design
External Validity
Analog Research
Independent Variable
Dependent Variable
Experimental Group in Research
Control Group in Research
Between-Subjects Experiment
Internal Validity
Example of an Experiment: Note-Taking Method and Learning Performance
Functional Relationship Between Independent and Dependent Variables
A researcher conducts a study to determine if the amount of sleep affects problem-solving skills. One group of participants is allowed to sleep for eight hours, while a second group is only allowed to sleep for four hours. The next morning, both groups are given the same set of puzzles to solve, and the researcher records how many puzzles each participant completes correctly. In this study, what is the independent variable?
Identifying Experimental Variables
Extraneous Variable
Treatment
Non-Experimental Research
Non-Manipulated Independent Variable
Operational Definition
Experimental Manipulation
Experimental Condition
Internal Validity
Manipulation Check
Null Result
In an experimental research study, how is an independent variable defined?
A researcher conducts an experiment to determine if a new cognitive exercise improves memory retention. They have one group practice the exercise daily while a second group does not, and then they measure both groups' memory test scores. In this study, the memory test scores represent the independent variable.
Match each psychology study description to the specific factor that serves as the independent variable in that research scenario.
A researcher is investigating how anxiety affects cognitive performance. Arrange the following methods of operationalizing the Independent Variable (IV) from the approach that provides the highest degree of internal validity (strongest causal evidence) to the approach that provides the lowest degree.
In a factorial research design investigating how both lighting conditions (bright vs. dim) and participant age (young vs. old) affect visual search speed, a researcher classifies both 'lighting' and 'age' as _____ variables because they are both hypothesized to be causes of the variation in search speed.
According to the definition of experimental research, what is the role of an independent variable in a cause-and-effect relationship?
True or False: In psychological research, an independent variable must always be manipulated by the researcher and can never simply be measured.
Match each research design scenario to the correct status of its independent variable (IV) based on the study's design.
In psychological research, the independent variable plays a central role in establishing causal relationships. Analyze how the definition and handling of the independent variable change when moving from a true experimental design to a non-experimental or factorial design. In your analysis, explain the relationship between manipulation, measurement, and the determination of cause-and-effect.
Evaluate the two proposed designs by analyzing how the independent variable (note-taking method) is handled in each. Justify which design provides stronger evidence for a cause-and-effect relationship based on whether the independent variable is manipulated or measured.
According to the principles of experimental research, what is the definition of an independent variable, and how does a researcher typically interact with it to observe its impact?
A social psychologist wants to determine if the number of bystanders present during an emergency affects how long it takes for an individual to help. The psychologist stages an emergency in a public space and systematically varies whether there are one, three, or ten other people present. The researcher then measures the time it takes for a participant to intervene and offer assistance. In this experiment, what is the dependent variable?
Example of an Experiment: Note-Taking Method and Learning Performance
Extraneous Variable
Time Series
Confounding Variable
Internal Validity
Null Result
Non-Experimental Research
In an experimental study, which of the following best describes the dependent variable?
In a psychological experiment investigating whether a new mnemonic technique improves memory recall, the students' memory recall scores represent the dependent variable.
Match each psychological research scenario with the specific dependent variable that would be measured to evaluate the presumed effect of the study's conditions.
A researcher investigates whether practicing mindfulness for ten minutes a day reduces anxiety scores on a standardized test. Arrange the logical steps for analyzing the role of the dependent variable in this investigation.
A researcher evaluates whether 'heart rate' or 'self-reported anxiety' is a more valid measure of the presumed effect in a study on stress. This judgment specifically addresses the quality and appropriateness of the ________ variable.
Suppose you are constructing an experimental protocol to investigate if 'ambient peppermint scent' improves 'cognitive focus' during a repetitive task. To create a valid dependent variable that measures the presumed effect of the scent, which of the following measurement strategies should you propose?
In a psychological experiment, the dependent variable is the factor that the researcher actively manipulates to determine its causal effect.
Match each core aspect of a dependent variable in a psychological experiment with the statement that best describes its function or behavior.
Learn After
Double-Blind Procedure
Extraneous Variable
Placebo Effect
Prioritizing Validities
Comparison of Internal Validity Across Research Designs
According to the provided text, what does internal validity indicate in an empirical study?
True or False: According to the text, a statistical relationship between regular exercise and happiness confirms that exercise causes happiness.
Match each research scenario or design category with the description of its setup and corresponding effect on internal validity.
A researcher conducts a study and finds a statistical relationship between regular exercise and happiness. Because this is a non-experimental correlational design, the study is low in _____ validity, as the researcher cannot confirm whether exercise causes happiness or if reverse causation is at play.
Evaluate the following research scenarios based on the provided text and order them from the HIGHEST level of internal validity (first) to the LOWEST level of internal validity (last):
Define 'internal validity' based on the provided text. In your answer, explain why experimental designs typically achieve high internal validity while non-experimental correlational designs exhibit low internal validity, referencing the specific examples mentioned in the text.
Based on the concept of internal validity described in the text, identify whether this study has high or low internal validity. Explain why this non-experimental correlational design cannot justify the researcher's causal conclusion, and describe at least one alternative explanation (such as reverse causation or extraneous factors) for the observed link.
A researcher wants to design an empirical study with high internal validity to test if a new tutoring program causes an increase in students' test scores. Based on the features of experimental research described in the text, how should the researcher structure their study's design to justify this causal conclusion?