Experimental Variables and Designs Quiz

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Questions and Answers

What role does a control variable play in an experiment?

It is the same as the dependent variable in the study.

It is a variable that is held constant to eliminate confounding effects. (correct)

It is a variable that is manipulated to create conditions.

It is the variable that researchers measure.

Which of the following provides a comparison condition in an experiment?

Treatment group

Placebo group

Manipulated variable

Control group (correct)

What is a design confound in the context of experimental validity?

A type of random variability that supports the experimental claim.

A methodological flaw that improves the internal validity of an experiment.

A situation where the dependent variable does not change.

An error made by the researcher in the manipulation of the independent variable. (correct)

What is the significance of ensuring temporal precedence in an experiment?

It demonstrates that one variable consistently follows another. Signup and view all the answers

How can selection effects threaten the internal validity of an experiment?

By causing systematic differences in participant characteristics between groups. Signup and view all the answers

What design refers to a scenario where a single group of participants is tested under all levels of the independent variable?

Within-subjects design Signup and view all the answers

What term is used for the phenomenon when participants' responses are influenced by their previous exposure to different conditions?

Order effects Signup and view all the answers

In a posttest-only design, how many times are participants tested on the dependent variable?

Once, after being assigned to conditions Signup and view all the answers

What is the main purpose of counterbalancing in experimental design?

To prevent carryover effects Signup and view all the answers

Which validity focuses on how well the variables were measured or manipulated within an experiment?

Construct validity Signup and view all the answers

What design utilizes random assignment to ensure different groups experience separate levels of the independent variable?

Independent-groups design Signup and view all the answers

What are demand characteristics in an experiment?

Cues that suggest the expected outcome to participants Signup and view all the answers

Which type of design tests participants' responses to multiple levels of an independent variable simultaneously?

Concurrent-measure design Signup and view all the answers

What is the aim of a pilot study in experimental research?

To provide preliminary data on the effectiveness of the manipulation Signup and view all the answers

What is statistical validity concerned with in research?

Whether the observed differences are statistically significant Signup and view all the answers

Study Notes

Experimental Variables and Designs

Experiment: Researchers manipulate one variable (independent) and measure another (dependent).
Independent Variable (IV): Manipulated variable; researchers control its value.
Dependent Variable (DV): Measured variable; records participants' responses.
Control Variable: Held constant to eliminate alternative explanations (confounds).
Comparison Group: Used to compare against the experimental group.
Control Group: Neutral condition; the baseline for comparison.
Treatment Group: Other levels of the independent variable.
Placebo Group: Receives an inert treatment (e.g., sugar pill).

Criteria for Causal Claims

Covariance: The IV and DV must co-vary (change together). Comparison groups allow this assessment.
Temporal Precedence: The IV must come before the DV in time. Researchers control the order.
Internal Validity: The study must rule out alternative explanations (confounds). A well-designed experiment minimizes these.

Threats to Internal Validity

Confounds: Alternative explanations for the results.
Design Confound: Researcher’s mistake in manipulating the IV, leading to systematic variability (ex: welcoming vs. unfriendly assistants).
Selection Effects: Participant differences between groups, making it unclear about cause.
Order Effects: Being exposed to one condition influencing the response to a later condition. Includes practice, fatigue, and carryover effects.
Demand Characteristics: Participants' cues that lead them to guess the study's hypothesis.

Minimizing Threats

Random Assignment: Assigning participants randomly to experimental conditions to balance extraneous variables across groups.
Matched Groups: Matching participants on key characteristics and assigning them randomly to conditions.
Counterbalancing: Presenting conditions in different orders to counter order effects; full counterbalancing involves every possible order.
Pilot Study: A preliminary study to test the effectiveness of an experimental manipulation.
Manipulation Checks: Additional measures to verify the manipulation of the independent variable (e.g., attitudes).
Unsystematic variability: Random fluctuations that do not systematically affect the results; not problematic

Independent-Groups Designs

Independent-Groups Design (Between-Subjects): Different participants are assigned to different levels of the IV.
Posttest-Only Design: Participants are randomly assigned to conditions and measured once.
Pretest/Posttest Design: Participants are measured before and after exposure to the IV.

Within-Groups Designs

Within-Groups Design (Within-Subjects): One group of participants experiences all levels of the IV.
Repeated-Measures Design: Participants are measured on the DV multiple times, after exposure to different levels of the IV (e.g., measure before and after a treatment).
Concurrent-Measures Design: Participants exposed to all levels of the IV simultaneously and a single preference is measured.

Interrogating Causal Claims with 4 Validities

Construct Validity: How well were the variables measured and manipulated? Including face validity and pilot studies.
External Validity: To whom and what can the causal claim generalize? random assignment helps
Statistical Validity: How well do the data support the causal claim? Includes significance and effect size.
Internal Validity: Are there alternative explanations for the results? Avoiding design confounds and selection effects are crucial.

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Description

Test your knowledge on experimental variables and designs with this comprehensive quiz. Understand key concepts such as independent and dependent variables, control groups, and criteria for causal claims. Perfect for students in psychology or research methodology courses.