Module 6: Basics of Experimentation

independent variable

A variable (antecedent condition) an experimenter intentionally manipulates.

levels of the independent variable

The two or more values of the independent variable manipulated by the experimenter.

control group

experimental group

two levels of the IV or the treatment conditions

dependent variable

It is the outcome measure the experimenter uses to assess the change in behavior produced by the independent variable.

operational definition

It is a clear, specific way of measuring or defining a variable in an experiment; it turns abstract concepts into measurable terms.

operationalizing

It means turning a conceptual definition into a measured or manipulated variable.

It defines terms in how you plan to measure.

conceptual definition

a researcher's definition of a variable at the theoretical level

experimental operation definition

measured experimental definition

two kinds of operational definition

experimental operational definition

A definition that specifies the exact procedure or steps for creating values of the independent variable.

measured operational definition

A definition that specifies the exact procedure for measuring the dependent variable.

reliability

it refers to the consistency of experimental operational definitions and measured operational definitions.

test-retest reliability

inter-rater reliability

inter-item reliability

types of reliability

test-retest reliability

It means the degree to which a person's scores are consistent across two or more administrations of a measurement procedure.

inter-rater reliability

It is the degree to which observers agree in their measurement of the behavior.

inter-item reliability

It measures the degree to which different parts of an instrument (questionnaire or test) that are designed to measure the same variable achieve consistent results.

split-half method

Two scores for each individual are obtained by splitting the test into comparable halves. This is usually achieved by assigning odd-numbered items to one form and even-numbered items to the other (odd-even split).

validity

it means the operational definition accurately manipulates the independent variable or measures the dependent variable

the rubber hand illusion

the feeling that an extraneous object, usually a rubber hand, is actually part of one's own body

internal validity

It is the degree to which changes in the dependent variable across treatment conditions were due to the independent variable.

high internal validity

it indicates a well-designed study that minimizes confounding variables and provides greater confidence in the causal inferences drawn.

external validity

It is the extent to which the results of a study can be generalized to subjects and/or conditions outside of the study.

face validity

It is the degree to which the validity of a manipulation or measurement technique is self-evident.

content validity

It means how accurately a measurement procedure samples the content of the dependent variable

How well a measurement covers all aspects of the concept it is supposed to measure

construct validity

It is how accurately an operational definition represents a construct.

criterion validity

· It says how well a test correlates with an established standard of comparison (i.e., a criterion).

a) predictive validity

b) concurrent validity

c) retrospective validity

three types of criterion validity

predictive validity

It means how accurately a measurement procedure predicts future performance.

concurrent validity

It shows the extent of the agreement between two measures or assessments taken at the same time. It compares a new assessment with one that has already been tested and proven to be valid.

retrospective validity

It is the extent to which an instrument that is purported to measure a particular behavior can be shown to correlate with past occurrences that demonstrate this behavior.

confounding variable

It is an extra factor that affects both IV and DV, making it hard to tell what caused the result.

extraneous variable

It is present when there are other variables that can affect experimental results, if we do not control them.

history threat, maturation threat, testing threat, selection threat, instrumentation threat, selection threat, subject-mortality threat, selection interaction

types of threat

history threat

It occurs when an event outside the experiment threatens internal validity by changing the dependent variable.

maturation threat

It is produced when physical or psychological changes in the subject threaten internal validity by changing the DV.

maturation

it refers to those processes such as growing older, growing stronger and even growing tired and impatient.

testing threat

It occurs when prior exposure to a measurement procedure affects performance on this measure during the experiment.

instrumentation threat

It is when changes in the measurement instrument or measuring procedure threatens internal validity.

human observer

Instrumentation threats are especially likely when the "instrument" is a ______________________

selection threat

It occurs when individual differences are not balanced across treatment conditions by the assignment procedure.

subject mortality threat or attrition threat

It occurs when subjects drop out of experimental conditions at different rates.

selection interaction

It occurs when a selection threat combines with at least one other threat.