Validity Flashcards
what is internal validity
the ability of your research design to test the hypothesis
for what it was designed for
= change in the independent variable caused change in the dependent variable
what can threat internal validity
- extraneous variables
2. confounding variables
extraneous variables
(alternative explanations for the observed effect) = rival hypothesis
confounding variables
= if two independent variables influence the dependent at the same level and you cannot distinguish which variable has actually caused the observed effect
Threats to internal validity
- History
- Maturation
- Testing (pretesting)
- Instrumentation
- Statistical regression
- Biased selection of participants
- Experimental mortality
Threat: History
multiple observations over time
-> different events can occur in between = affecting the results
Threat: Maturation
Effect of age or fatigue
- can affect performance changes (confounding variable)
- cannot difference which variable caused the outcome
Threat: testing
making pretests before the actual treatment
- subjects get presensitized
= better performance afterwards
Threat: Instrumentation
unobserved changes in an criteria or measurement instrument.
- difficult to distinguish what caused the actual response
Statistical regression
if you have chosen participants which an extreme score,
- Tendency in the second test/measurement = regression to the population mean
Biased selection of participants
initial differences in the subjects–> leads to changes in the performance/results
- cannot separate the effect of the independent variable
Experimental Mortality
participants drop out of the study due to death, moving
external validity
study results can be generalized beyond the research setting
- applying to real world problems
What is the aim of for external validity ?
gaining inside into the underlying mechanisms of the studied behavior
Threats to external validity
- Highly controlled laboratory settings
- Reactive testing
- Interaction: selection particip. bias and IV
- reactivity of experimental arrangements
- multiple treatment inference
reactive testing
pretest influences participant’s reaction on an experimental variable.
Interaction: selection bias
study results can only be applied to studied group of subjects (e.g college students, gender )
Reactivity of the experimental arrangements
- artificial setting of the experimental situation
- participant’s knowledge that they part of the study
multiple treatment inference
- treatment in the first condition may affect the performance in the later condition (e.g. fatigue)
Problem with internal and external validity ? interaction
if one increases the other usually decreases
What kinds of research settings are available ?
- Laboratory setting
2. Field setting
What are the characteristics of the laboratory setting ?
=mostly artificial setting
+ control over extraneous variables (which could affect your dependent variable)
subcategory: simulation
What are the characteristics of the field setting ?
= studying behavior in naturally environment
+ higher generalization
- no control over extraneous variables (confounding variables)
What is a sample?
small subgroup of a larger population
What does generalization mean?
that you can apply the findings of your sample study to the larger population
What does random sample mean
if you sample randomly, every person has the equal chance of being chosen for your study
Why do we use random sampling
- highest level of generality
- if you have the intention to apply it directly to real-life problems
What is deception
when you either actively or passively mislead the participant
- withholding information about the experiment
What types of deception do we have ?
- active deception
2. passive deception
What means active perception ?
That you really have the intention to withhold information about the study
- misleading the purpose of the study
- making false promises to the participants
- providing misleading information to the participant
- using placebos and not mentioned drugs
- using pseudo-participants
What is passive deception?
- unrecognized conditioning of the participants
- concealed/invisible observations
- unrecognized participant observations
- using projective techniques and other personality tests
Non response bias
if a large part of your participants fail to give answer you back or send you back the questionnaire
What are the categories of deception?
- Intentional deception
2. Unintentional deception
Intentional deception
not fully report details of your study
Unintentional deception
not fully informing your participants what is the study about and what does it involve
What is the problem with deception
elaborate hoax
- damage trust into research (less likely to act as a volunteer again in future studies
What are the solutions for deception?
- Role play
- inform the participant that deception will be used
- Debriefing
What is economic sampling ?
that you have enough participants to ensure that your study will be valid
Factors of economic sampling ?
- Amount of acceptable error
2. Expected magnitude of the populations
What is sampling error ?
that the characteristics of the sample differ from the characteristics of the population
What means debriefing ?
informing the participant after the study about used deception and the general purpose of the study
Goal: restore participant’s self esteem
