Artifacts and biases Flashcards
Artifacts and biases can…
Threaten the validity of an experiment
Artifact
Extraneous influence
Includes all of the variables that the experimenter is not interested in examining
Virtually unlimited number of factors
Artifact or bias?
Depends on the focus on the investigation
Influences commonly identified as artifacts evolve through stages
ICE
- Ignorance
- Coping
- Exploiting
Ignorance
First stage of artifact influence
Investigator = unaware
When source of artifact is posed, may be denied
Coping
Second stage of artifact influence
Existence and possible importance of artifact = recognized
Implement control procedures to direct, estimate, reduce, or prevent its impact
Exploiting
Third (final) stage in artifact infl
Rather than try to minimize its impact -
“Artifact” becomes an area of research
Sources of biases
Investigator
Experimenter
Investigator
Individuals designing the experiment
Experimenter
Individuals executing the experiment
Nature of the problem w rationales, scripts, and procedures
Potential sources of biases incl instructions and experimental materials or procedures in which the subj is exposed
Scripts
Major source of bias - can result from imprecision
Script = specific activities, tasks, and instructions administered by the experimenter
Loose protocol effect
Failure of investigator to provide well-specified script
Problems resulting from failure to specify how experimenter should behave
- Investigator won’t know what was actually done w the subjs
- Inconsistencies obscure the effects of the data and introduces “noise”
Within grp variability (error variance) = increased
Recommendations for script etc problems
- Procedures should be explicit and standardized
- Use automated or previously taped procedures
- Anticipate range of questions that may arise and provide guidelines for answering them
- Train experimenters together
- Incl confederates (increases vigilance)
- Interview subjs after to evaluate consistency of experimenters
- Encourage experimenters to report deviations from the script
Experimenter expectancy effects - nature of the problem
Source of potential bias
Effects refer to the infl of the experimenters’ beliefs and desires about the results on how the subj performs
Effects considered unintentional
Inapprop statistical analyses or selective omission of data
Expectancies can systematically relate to teh magnitude of expectancy effect
Pose a threat to construct validity
Recommendations for experimenter expectancy effects
- Double blind study
- Use different staff for data collection and administration of intervention
- Use manuals
Experimenter characteristics - nature of the problem
Characteristics of the experimenters may infl subj bx
Incl age, gender, race, friendliness, etc.
Usually - only restricts external validity - relationship w IV and DV may only hold up w experimenters who have specific characteristics
Threaten construct validity when one experimenter administers one condition and the other administers another
Tp characteristics infl outcome incl level of empathic understanding, amt of experience, degree of openness, and directness