Task 6. Setting up research & sampling

Question 1

Population

Answer 1

• all possible participants that fit the criteria

Question 2

Sample

Answer 2

• smaller subgroup chosen from the larger population

Question 3

Generalization

Answer 3

• ability to apply findings of a sample to a larger population
• requires a representative sample
• one of the important factors for external validity

Question 4

Random sample

Answer 4

• every person in the population has an equal chance of being chosen, necessary for generalization, but difficult to obtain

Question 5

Nonrandom sample

Answer 5

• individuals chosen from a highly specialized subpopulation

Question 6

Internet research sampling

Answer 6

• nonrandom, highly specialized, large but not representative (only ppl w )

Question 7

Animal studies sampling

Answer 7

• strains need to be exactly the same, usually the exact same litter because any kind of genetic mutation can affect the results

Question 8

Factors to consider when acquiring a research sample

Answer 8

1) research setting: lab or field
2) special needs of research: screening
3) ethical guidelines: APA

Question 9

Volunteer bias

Answer 9

• individuals that volunteer fundamentally different from the ones that don’t, lowered external validity

Question 10

Situational factors of volunteers

Answer 10

• interesting / important topis
• rewards
• personal acquaintance with the researcher

Question 11

Internal validity and volunteerism

Answer 11

• volunteers are trying to please the experimenter, altering the results
• volunteerism can serve as “motivation indicator”

Question 12

External validity and volunteerism

Answer 12

• WEIRD participant characteristics -> low generalizability

Question 13

Remedies for volunteerism

Answer 13

• making the appeals as interesting as possible
• make appeal as nonthreatening as possible
• state in what way the participants are important-> benefitting others
• ​if possible avoid stressful tasks
• ​personalized appeals

Question 14

Probability sampling

Answer 14

• each participants has a known probability of being in the sample -> ideally, all have an equal chance

Question 15

Representative sample

Answer 15

• closely matches the characteristics of a population

Question 16

Biased sample

Answer 16

• non-representative sample

Question 17

Sampling techniques (5)

Answer 17

• simple random: random selection of a certain # of individuals
• stratified: population divided into segments, each segment represented
• proportionate: conserve the percentage of the population segments
• systematic: every nth individual is included, random start
• cluster: picking a naturally occurring cluster of individuals, including the entire group (used together with simple random)

Question 18

What to keep in mind when determining Sample size

Answer 18

• smaller samples- controlled environment
• larger samples - many variables/uncontrolled variables

-amount of acceptable error
-expected magnitude of population proportions

Question 19

Economic sample

Answer 19

• enough participants to be valid, but no more

Question 20

Internal validity

• extraneous variables?
• confounding?

Answer 20

• ability of research design to adequately test your hypothesis / ability to adequately measure what its supposed to
  -shown in variation in independent variable
• threatened by extraneous variables that can provide alternative explanations and rival hypotheses
• confounding: merging of two or more variables to the point that it is impossible to separate their effects, affects overall correlation

Question 21

Threats to internal validity

general sources of confounding (7)

Answer 21

• history: special events occur between obs.
• maturation: performance affected due to aging/fatigue
• repeated testing
• instrumentation: missed errors in criterion/instruments
• statistical regression: extreme-result subjects selected for treatment tend to regress toward the mean upon retesting
• biased selection: groups not equivalent prior to intervention
• experimental mortality: loss of subjects during the research

Question 22

External validity

Answer 22

• results can be generalized for the population

Question 23

Threats to external validity

Answer 23

• reactive testing: subjects react to pretest and adjust
• interaction between participant selection bias and the IV: Jožek iz Špičkovine vs Maartje van Maasi
• reactive effects of experimental arrangements: being aware that one is a participant and that they are being studied
• multiple treatment interference