1.) Hawthorne effects: behavioral changes due to the fact that they know they are being studied. - increased light improved participants' performance, dimmed lights also improved performance. Finding: attention is what improved performance, not light
Measurement validity & reliability
o Does the measure give accurate results?
Measurement validity is important part of internal validity
o Internal validity: the accuracy of an investigations results as
influenced by the planning,
Sampling Non-probability sampling
Things to know by the end of the lecture
o How is non-probability sampling different from probability
o Why and when do we use non-probability sampling?
o What are the non-probability sampling techniques?
accuracy of a studys results based on its design and execution
o measurement reliability and validity
o procedures used in data collection
o a set of possible threats to validity
Factors Influencing Internal Validity
Survey / interview method Functions
Both survey and interview are self report techniques.
Able to serve two functions
document current conditions
E.g., Opinion poll
describe and explain why conditions occur
What are underlyi
Things to know by the end of the lecture:
o Know advantages and disadvantages of experiments
o Know how to achieve experimental control to get causal inference
Factors influencing control
Specific techniques to ensure control
o Know the var
Posttest-Only Nonequivalent Groups Design (means no random
o Static group comparison design
o true and full experiment = random assignment only!
o Non-randomly assigns research participants to a treatment o