Exam 2 Flashcards
(42 cards)
Extraneous Variables
Influence of unrelated factors when not controlled
Validity
The overall amount of control put in place to tightly restrict confounding effects
Confounding Effects
Other factors that could’ve effected your results that you didn’t expect to effect your validity
Active Variables
Can be manipulated by researcher; subjects assigned to different levels of IV
Processes of Validity in Research
The experimental variables
Sampling technique/Strategy
Controls (extraneous factors/experiment itself to have relevance to clinical practice)
Analysis of Results
ITT
Avoids bias post-randomization and over-estimation of treatment effects
Design Strategies for Inter-Subject Differences
Inclusion Criteria Blocking Variable Matching Subjects Using Subjects as own Control ANCOVA
ANCOVA
Analysis of Covariance
-Theoretically removes the confounding influences of extraneous factors
Internal Validity
The degree to which the relationship between the independent and dependent variables is free from the effects of extraneous factors
External Validity
The degree to which the results of a study can be generalized to persons or settings outside the experimental situation
**inc in IV = dec in EV
4 Threats to Validity
Statistical Conclusion Validity
Internal Validity
Construct Validity of Causes and Effects
External Validity
Construct Validity
To what theoretical constructs can results be generalized?
Statistical Conclusion Validity
Is there a relationship between the IV and DV?
What can lead to invalid stat conclusions?
Low statistical power
Violated assumptions of statistical tests
Error Rate
Reliability and Validity
Power Analysis
Uses number of subjects enrolled into your study
-you need 80-90% or above
Power
The ability of a statistical test to reject the null hypothesis
-will tell you the minimum # of subjects you need in control/experimental group to reject the null hypothesis
Temporal Precedence
The cause precedes the effect
Ex. What is the effect of caffeine of the level of anxiety? If you have smokers in your study you do not want them to smoke 24 hrs before study
4 Threats to IV- Single Group Threats
History
Maturation
Attrition
Instrumentation
Experimental Bias
Biases introduced because of participant or researcher expectation
Hawthorne Effect
Participants experience change as a result of simply being in a research project
Rosenthal Effect
Researcher’s behaviors or appearance impact how the participant responds
Avis Effect
Participant in control group try harder simply because they are in the control group
Threats to External Validity
Interaction of Tx and Selection
-becomes a problem if samples are confined to certain types of participants
Interaction of Tx and Setting
Interaction of Tx and History
-cannot generalize results to different periods of time
Reactive or Interactive Effects of Testing
-pretests make a participant more aware or sensitive to upcoming tx
Quasi Experimental Designs
Similar to Experimental Designs expect that they lack randomization or comparison group OR BOTH
-cannot rule out all threats to IV