Task 3 Flashcards
Dependent variable
• “Outcome variable” • Measurable • Influenced by change in condition Example: Is reaction time decreased by drinking coffee?
Independent variable
• “Condition”
• Directly altered by experimenter
Example:
Is reaction time decreased by drinking coffee (eg 1cup, 2cups, 3cups)?
Which question should you ask while thinking about the reliability of your experiment?
How similar would the result be if the experiment is repeated?
Which question should you ask by thinking about the validity of your experiment?
Does the measure actually measure what the researcher intends to measure?
Name 3 sources of variability
- precision of measure: variability due to imperfections in measuring tool
- Interrater Reliability: variability due to differences in judgments of observer
- Marion of error: variability due to individual differences within a sample
Test-retest reliability
- Similarity of result if test is repeated
* Best for assessing stable characteristics
Name 3 problems of test-retest reliability
- Remembering of questions
- Longer interval between tests needed
- Change in participant between tests
explain parallel/ alternate-forms reliability
-equivalent questions are asked
- can be administered after each other
2 tests with a bigger time difference
Name 2 problems of parallel / alternate-forms reliability
• Equivalence of questions
• Change in participant between tests
one bigger test at one time
Explain split-half reliability
• One bigger test is administered
• Equivalent questions are repeated
• Results of equivalent questions are scored
individually
What is the problem of Split-half reliability?
Equivalence of questions
What is the accuracy of measure by validity?
- Comparing to a standard
* Biased if scores differ on average from standard
What do you know about the observer bias? What is the solution?
- May arise of researcher has a desired outcome in mind
* Solution: Blind observers (Researcher do not know condition of participant during experimentation)
Name 4 types of validity
- Face Validity
- Content Validity
- Criterion-related Validity
- Construct Validity
Face Validity
test seems to test what it is explained to test. Perceived legitimacy of the test can influence participants’ attitude
Content Validity
test actually tests what it is designed to test.
Criterion-Related Validity
Compare your results with someone else
• Concurrent: agreement with “golden standard” (right now)
• Predictive: successful prediction of future behavior
Construct Validity
- Convergent (similar to instruments measuring the same construct) you compare to a other test from the same area and want to get similar results
- Divergent (not similar to measure of a different construct) you compare to a test of another area and want to have different results
What is internal validity?
- Ability of your research design to adequately test your hypothesis
- Showing that the variation in the independent variable caused the observed effect
Name 2 threats (Bedrohungen) of internal validity?
• Rival hypothesis: another alternative variable might explain the effect
Alternative explanations
• Confounding: combination of variables explains the effect and one cannot separate the effect of these variables
Name 8 sources of confounding (Störeinfluss)
- History: specific events other than treatment occur between observations (eg. 9/11)
- Maturation: fatigue or aging change performance over time
- Instrumentation: instrument calibration changes and confounds the effect
- Statistical regression: subjects selected for treatment on the basis of their extreme scores tend to move closer to the mean when retesting
- Biased subject selection: nonrandom
- Experimental mortality / attrition: dropouts (is mainly a problem if its a random dropout (experiment gets to heavy pat. drops out)
- Demand characteristics: participants know
the purpose of the study and behave differently - Placebo effect: participants get better because they believe that they receive an effective treatment
What is external validity?
ability of your research design to generalize the results beyond the research setting to real world situations
Name 4 threats of external validity
- reactive testing
- interactions between participant selection biases and independent variable
- reactive effects of experimental arrangements
- multiple treatment interference
reactive testing
pretests may affect reaction to the experimental test