Confounding and Obscuring Variables Flashcards

Comprehensive vocabulary flashcards covering internal validity threats, obscuring variables, null effects, statistical validity guidelines, and power based on lecture notes by Dr. Liz Shin.

Construct Validity

The degree to which a study accurately measures and manipulates the operationalized variables under investigation.

External Validity

The extent to which the causal claims and findings of a study can be generalized to other people or situations.

Statistical Validity

The extent to which statistical conclusions drawn from a study are accurate and reliable, addressing effect size, estimate precision (such as a $95\%$ CI), and statistical power.

Internal Validity

The ability of a study to demonstrate that the independent variable, and not alternative explanations or confounds, caused the observed effect on the dependent variable.

Manipulation Check

An extra dependent variable inserted into an experiment to test whether the experimental manipulation worked as intended.

Pilot Study

A simple study completed before (or sometimes after) the primary study to test and refine procedures and manipulations.

Cohen's Guidelines for Effect Size Strength

Benchmarks for evaluating effect size strength where $d = 0.20$ is small or weak (comparable to $r = .10$), $d = 0.50$ is medium or moderate (comparable to $r = .30$), and $d = 0.80$ is large or strong (comparable to $r = .50$).

One-Group Pretest/Posttest Design

A flawed research design in which a single group of participants is measured on a dependent variable before treatment, administered a treatment, and then measured again after treatment.

Maturation Threat

A threat to internal validity in which changes in participants occur naturally over time independent of the experimental treatment.

History Threat

A threat to internal validity occurring when external events take place during the study that influence participants' responses or behaviors.

Regression Threat

A statistical phenomenon in which extreme scores on a variable move closer to the group mean upon retesting.

Attrition Threat

A threat to internal validity caused by the systematic loss of participants from a study over time, biasing results if dropouts differ systematically from remaining participants.

Testing Threat

A threat to internal validity in which exposure to a pretest measure alters or influences participants' scores on the subsequent posttest measure.

Instrumentation Threat

A threat to internal validity occurring when a measuring instrument, observer, or coding standard changes over time during the study.

Observer Bias

A threat to internal validity occurring when researchers' expectations or beliefs unintentionally influence their observations or interpretation of the data.

Demand Characteristics

Cues in an experiment that lead participants to guess the study's hypotheses or expectations and alter their behavior accordingly.

Placebo Effect

An improvement in outcomes occurring solely because participants believe they are receiving an effective treatment, even when the treatment is inactive.

Double-Blind Study

An experimental procedure in which neither the participants nor the researchers observing them know who is in the treatment group or the control group.

Masked Study

An experimental procedure in which participants know their group assignment, but the observers or raters assessing them do not.

Null Effect

A finding that the independent variable did not produce a statistically significant difference on the dependent variable.

Weak Manipulation

An operationalization of the independent variable that lacks sufficient strength to produce a noticeable or measurable difference between experimental groups.

Insensitive Measure

A dependent variable measurement tool that cannot detect subtle or small differences between groups or conditions.

Ceiling Effect

A restriction in score distribution occurring when a measured variable has an upper limit, causing scores to cluster at the high end of the scale.

Floor Effect

A restriction in score distribution occurring when a measured variable has a lower limit, causing scores to cluster at the low end of the scale.

Measurement Error

Any factor that inflates or deflates a participant's true score on a dependent variable, creating within-group variability.

Individual Differences

Variations in personal traits, characteristics, or behaviors across participants that spread out scores within an experimental group.

Situation Noise

External environmental distractions or factors that introduce within-group variability and obscure true differences between groups.

Statistical Power

The probability that a study will yield a statistically significant result when the independent variable actually has a true effect.

Publication Bias (File Drawer Problem)

The tendency for academic journals and researchers to publish studies with statistically significant results far more frequently than studies showing non-significant or null findings.