internal vs external

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Questions and Answers

What is the definition of internal validity?

Internal validity refers to the degree to which a study can establish a cause-and-effect relationship between the independent variable (IV) and the dependent variable (DV). It focuses on ruling out alternative explanations for the observed results.

What are the key characteristics of high internal validity?

High internal validity means the study successfully isolates the effect of the IV on the DV, with minimal influence from confounding variables.

What are the key terms associated with internal validity?

The key terms associated with internal validity are confounding variable, experimental control, and causality.

Define a confounding variable.

A confounding variable is an external factor that influences the DV and is related to the IV, creating an alternative explanation for the results. Signup and view all the answers

What are experimental control techniques?

Experimental control techniques are used to eliminate or minimize confounding variables, such as random assignment and blinding. Signup and view all the answers

Define causality.

Causality refers to the direct relationship between two variables where one directly affects the other. Signup and view all the answers

What are some common threats to internal validity?

Common threats to internal validity include history effects, maturation, testing effects, instrumentation, selection bias, attrition, and demand characteristics. Signup and view all the answers

Which of the following is an example of high internal validity?

A randomized controlled trial (RCT) where participants are randomly assigned to a new drug group or placebo group, and confounders are controlled. Signup and view all the answers

Define population validity.

Population validity refers to the degree to which results can be generalized to the broader population. Signup and view all the answers

Define ecological validity.

Ecological validity refers to the extent to which the study setting reflects real-world conditions. Signup and view all the answers

Define temporal validity.

Temporal validity refers to the generalizability of results across different time periods. Signup and view all the answers

Which of the following is an example of low external validity?

A study on anxiety using a small, homogeneous sample of undergraduate psychology students, tested in a lab environment. Signup and view all the answers

How do internal validity and external validity often trade off?

Studies with high internal validity, such as tightly controlled lab experiments, often sacrifice external validity because they may not represent real-world conditions. Conversely, studies with high external validity, such as field studies, often have lower internal validity due to the lack of control. Signup and view all the answers

How can researchers maximize both internal and external validity?

Researchers can maximize both internal and external validity by using random sampling and assignment techniques, conducting replication studies, and ensuring that their research is conducted in diverse settings and populations. Signup and view all the answers

What is internal validity, and how can it be threatened in experimental research?

Internal validity refers to the degree to which a study can establish a cause-and-effect relationship between the IV and DV. It focuses on ruling out alternative explanations for the observed results. Internal validity can be threatened by confounding variables, which are extraneous factors that can influence the DV and make it difficult to isolate the effects of the IV. Signup and view all the answers

Provide an example of high internal validity and low external validity in a psychological experiment.

A highly controlled laboratory experiment examining the effects of a new drug on memory could have high internal validity if researchers carefully control for confounding variables. However, the results of this experiment may have low external validity if they cannot be generalized to real-world settings and populations. Signup and view all the answers

Define ecological validity and describe how it relates to external validity.

Ecological validity refers to the extent to which the study setting reflects real-world conditions. It is closely related to external validity because it considers the generalizability of findings to real-world settings and populations. Signup and view all the answers

How can a researcher improve both internal and external validity in the same study?

Researchers can improve both internal and external validity by carefully designing their study to control for confounding variables while also ensuring that the sample, setting, and procedures are representative of the real world. Signup and view all the answers

Why might a highly controlled lab experiment lack generalizability?

A highly controlled lab experiment may lack generalizability because the artificial conditions and controlled setting may not accurately reflect real-world situations. The results of such experiments may not be applicable to other settings, populations, or times. Signup and view all the answers

Study Notes

Internal Validity

Internal validity refers to the degree to which a study can confidently establish a causal relationship between an independent variable and a dependent variable.
High internal validity means that the study's design effectively rules out alternative explanations for the observed results.

Characteristics of High Internal Validity

Clear manipulation of the independent variable: The researcher must effectively control and manipulate the independent variable to isolate its effects.
Control of extraneous variables: Factors other than the independent variable that could influence the dependent variable should be minimized or controlled.
Random assignment of participants to conditions: This procedure ensures that groups are equivalent at the start of the study, reducing the likelihood of pre-existing differences influencing the results.

Key Terms

Confounding variable: A variable that is not the independent variable of interest but can also influence the dependent variable. This can lead to spurious correlations and make it difficult to determine the true effect of the independent variable.
Causality: A causal relationship exists when a change in one variable directly leads to a change in another variable.
Experimental control techniques: These are methods used to minimize the influence of extraneous variables. Examples include random assignment, holding extraneous variables constant, and using control groups.

Threats to Internal Validity

History: Uncontrolled events that occur during the study that could influence the dependent variable.
Maturation: Changes in participants over time (e.g., growth, learning) that could influence the dependent variable.
Testing: The act of taking a test can influence performance on subsequent tests, even if the content is different.
Instrumentation: Changes in the measurement instrument or procedures used during the study.
Regression to the mean: When individuals with extreme scores on a measure tend to score closer to the average on subsequent measures.
Selection: Pre-existing differences between participants in different groups that could influence the dependent variable.
Attrition: Participants dropping out of the study, potentially creating bias in the results.

External Validity

Population validity: The extent to which the results of a study can be generalized to different populations.
Ecological validity: The extent to which the results of a study can be generalized to real-world settings.
Temporal validity: The extent to which the results of a study can be generalized across time periods.

Examples of High Internal and Low External Validity

A highly controlled laboratory experiment with a strong manipulation of the independent variable might have high internal validity because it effectively isolates the causal relationship between the independent and dependent variables. However, it may have low external validity as the results may not generalize well to real-world settings.

Relationship Between Internal and External Validity

Often, there is a trade-off between internal and external validity. Studies designed to maximize internal validity often sacrifice external validity and vice versa.

Maximizing Both Internal and External Validity

Researchers can use a combination of experimental control techniques and strategies to maximize both internal and external validity. These include:
- Using multiple measures of the dependent variable.
- Replicating studies in different settings.
- Sampling diverse populations.
- Using mixed methods (e.g., qualitative and quantitative data).

Ecological Validity

Ecological validity relates to the extent to which the findings of a study can be generalized to real-world settings. It emphasizes the relevance and applicability of the research context to everyday experiences. Low ecological validity suggests that the results might not be representative of real-world situations.

Improving Both Internal and External Validity

Researchers can combine different strategies to improve both internal and external validity, such as:
- Using a combination of controlled experimental conditions with real-world data collection methods (e.g., field studies).
- Including diverse participant samples that mirror the target population.
- Replicating studies in different contexts to assess the generalizability of findings.

High Control, Low Generalizability

A highly controlled laboratory experiment can have the advantage of strong internal validity by effectively isolating the variables of interest. However, this controlled environment can sometimes lead to a lack of generalizability. Findings in a controlled setting might not accurately reflect how the variables interact in more complex, real-world scenarios.

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