Session 7 Flashcards
The two types of Experimental Designs are…
- Causal
2. Correlational
Causal Experiments mean that…
one variable directly or indirectly influences another
Correlational Experiments mean that…
changes in one variable accompany changes in another
What are the Three Criteria for Causal Relationships?
- co-variation between X and Y variables
- Temporal sequence, X occurs before Y variable
- Control of third (extraneous or confounding) variables
When the behaviors and characteristics of the researcher influence the reactions of participants, it is called…
Researcher Error
When the personal characteristics and experiences of participants influence their responses, it is called…
Participant Error
When aspects of the environment influence scores, it is called….
Environmental Error
When aspects of the stimuli presented (the IV) or measurement procedure employed influence scores, it is called…
Measurement Error
What is the definition of Third Variables?
- Any variable that can potentially influence results, but is NOT intended by the researcher
2, Any variable that may compete with the IV in explaining the outcome of the study (DV)
How do Third Variables influence research?
- By influencing the scores & thus the mathematical relations produced.
- Leads to errors when interpreting and generalizing the study, because the variables that we think are operating are not those that are really operating
What is a Dis-simulation effect?
Third variable result of increase in scores
What is a masking effect?
Third variable result of decreasing scores
What is the definition of an Extraneous Third Variable?
- Any variable that can potentially influence results, but is NOT intended by the researcher
2, Any variable that may compete with the IV in explaining the outcome of the study (DV)
How do Extraneous Third Variables influence research?
- By influencing the scores & thus the mathematical relations produced.
- Leads to errors when interpreting and generalizing the study, because the variables that we think are operating are not those that are really operating
What is a masking effect?
Third variable result of decreasing scores
How does an Extraneous Third Variable fluctuate?
- unsystematically, randomly, no consistent pattern
2. systematically, consistent pattern
What are the two types of Third Variables?
- Extraneous Variables
2. Confounding Variables
What is a Confounding Variable
- an extraneous variable the DOES compete with the IV in explaining the outcome of the study
- Systematic variation in an extraneous variable
List FOUR examples of Confounding Variables
- Hawthorne (Attention) Effect
- John Henry Effect
- Placeo Effect
4 Demand Characteristics
List FOUR examples of Confounding Variables
- Hawthorne (Attention) Effect
- John Henry Effect
- Placeo Effect
4 Demand Characteristics
What is another name for the Attention Effect?
Hawthorne Effect
What happened in the Hawthorne Effect?
Workers productivity went up when lighting was increased AND when it was decreased
What is the interpretation of the Hawthorne Effect?
workers respond to researcher attention whether or not the lighting was increased or decreased
What controls were used in Hawthorne Confound?
- Experimental group
- control receiving attention
- control NOT receiving attention
What is the John Henry Effect?
possibility that the control group might become aware of its ‘inferior’ status and respond by trying to outperform the experimental group
What is the John Henry Effect controlled by?
concealing the control group’s knowledge of its status
What is the Placebo Effect?
tendency of individuals to improve (or feel improved) simply because they know they are being treated
Placebo Effect controlled by…
giving the control group a placebo which provides treatment for the control group
What is a Demand Characteristic?
a cue that lets participants know the expected outcomes of an experiment
Demand Characteristics are controlled by….
concealing researcher expectations from participants
Confounding is a threat to _________ ____________?
Internal Validity
What is Internal Validity?
- the degree to which the relationship between the scores reflects only the relationship between the intended variables
- Changes in the Y (DV) related directly and only to changes in the X (IV)
What is Internal Validity?
- the degree to which the relationship between the scores reflects only the relationship between the intended variables
- Changes in the Y (DV) related directly and only to changes in the X (IV)
List 7 Common threats to Internal Validity.
- History
- Maturation
- Instrumentation
- Testing
- Statistical Regression
- Selection Bias
- Mortality
What are 2 factors in Historical threats to Internal Validity?
- environmental influences between pre and post tests
2. non-treatment events occurring between observations
Name 2 Factors in Maturational Threats to Internal Validity.
- participants age between pre and post tests
2. performance changes due to aging and confounds the effect of the treatment
Name 2 Factors in Instrumentational threats to Internval Validity.
- Potential changes in measurement procedures from pretest to post test administration
- unobserved change in observer criteria or instrument calibration confound the effects of treatment
Name 2 Factors in Testing Threats to Internal Validity
- learning occurs during pretest and affects post test results
- testing prior to treatment changes how people respond in post-testing
What is the statistical regression threat to internal validity?
participants selected for treatment on the basis of their extreme scores tend to move closer to the mean on retesting
What is the Selection Bias threat to internal validity?
nonequivalent initial groups used
What is the Mortality threat to internal validity?
differential loss of participants from the groups to be compared resulting in nonequivalent groups
What is the single best approach to controlling threats to Interval Validity?
Experimental Design that incorporates random assignment of participants to experimental and control groups
List FOUR Common threats to External Validity.
- Interaction of Selection Bias with IV
- Reactive effects of experimental arrangements
- Reactive effects of testing (pretest sensitization)
- Multiple Treatment Interference
Describe the Interaction of Selection Bias with IV (threat to External Validity)
- If a biased sample of participants is used in an experiment, a researcher will not know whether the effects of the treatment can be expected if the treatment is administered to the entire population
- Results of the study may only pertain to the particular type of participants that were included in the study
Interaction of Selection Bias with IV is controlled by…..
random selection
Describe the Reactive effects of experimental arrangements (Threat to external validity)
- If the experimental setting is different from the natural setting in which the population usually operates, the effects that are observed in the experimental setting may not be generalized to the natural setting
- The presence of observers, instrumentation, or the lab environment that affects the participant but would not occur if the participant had been in a natural setting
Reactive effects of experimental arrangements is controlled by….
experiments conducted under natural conditions when possible
Describe Reactive effects of Testing (pretest sensitization). (Threat to External Validity)
- Possibility that the pretest might influence HOW the participants respond to the experimental treatment
- Pretesting may decrease or increase the sensitivity of the participants to the IV. Thus, one might not be able to generalize to non-pretested individuals.