Literature ReviewsEthics

Sampling

Sampling Plan Due 2/14

Literature reviews

• Purpose– Place each work in the context of its contribution

to the understanding of the subject under review – Describe the relationship of each work to the

others under consideration – Identify new ways to interpret, and shed light on

any gaps in, previous research – Resolve conflicts amongst seemingly contradictory

previous studies – Identify areas of prior scholarship to prevent

duplication of effort – Point the way forward for further research – Determine where your work will fit

Literature Reviews

• Hopefully by the end of this class you will become a more critical consumer.

• Questions you should ask when reading a report– What were the research questions?– Who or what was studied?

• How were they sampled?– What are the variables?

• How were they measured?– What design was used?– What statistics were used?– Do the conclusions follow from the statistics?

Writing Literature Reviews

• Avoid summarizing a body of literature– Attempt to identify shortcomings– Provide analysis

• Design problems• Problems with measures• Unique subsets of the population not included

• Be very very careful– Plagiarism can sneak up on you

The Ethics of Using Human Participants

The History of Human Participants Ethics

• The Need for Action– Nazi Doctors– The Tuskegee Syphilis

Experiment (1930 – 1972)

– The Milgram Study (1961-1962)

• The Nuremburg Code

1974• The Belmont Report

– Respect for Persons

– Beneficence

– Justice

• The National Research Act– Research plans must be approved

– Do no harm (physically or mentally)

– Informed Consent

• The Family Educational Rights and Privacy Act (The Buckley Amendment)– Confidentiality of Data

– “Legitimate Educational Interest”

Informed Consent• Participant must be aware of what they will

be asked to do in the study. • Participant must freelyfreely choose to participate.

(“participants are given explicit assurances of the voluntary nature of their involvement”)

• Consent must come from guardian for minors and those with diminished capacity. They themselves should give assent.

Informed Consent• Participants are free to withdraw at any at any

time. time. • Information should be given in language

the participant can understand. • The information should help them decide

whether to participate. • Information must include risks and

benefits.

Confidentiality

• Personally identifying information will be minimized

• Access to data and all records will be restricted to those with Legitimate Interest

• Anonymous vs. Confidential Participation

Three Levels of IRB Review• Exempted Review

– Secondary Data– Surveys, Interviews, Public Observations, Educational Tests– Educational Settings

• Expedited Review– Studies involving minimal risk– Studies involving children, prisoners, pregnant women, mentally

disabled, in-vitro fertilization, “other vulnerable populations”– blood samples, other biological specimens collected without invasion– “collection of data from voice, video, digital, or image

recordings made for research purposes”• Full Review• ALL RESEARCH SHOULD BE REVIEWED.

(Schuster, et al., 1998)

Surveyed Asian and Pacific Islander high school studentsregarding their sexual practices. Individuals unaffiliated withschool proctored the survey. The school district notifiedparents of the survey and gave them the opportunity to sign a form denying permission for their children to participate. Students could also decline participation, and the names ofthe students completing the survey were not recorded.Respondents were instructed to skip items they preferred not to answer.

What aspects of the study cause concern?

Ethical Issues

• A questionnaire on alcohol use seeks information about growing up in an alcoholic family.

• Students in an intro psychology class get extra credit for participating in an experiment.

• Respondents to a survey are offered monetary compensation for completing the survey.

• A questionnaire on workplace stress asks teachers how often they drink alcohol.

Havasupai Issue

• What happened to the Havasupai?

• Why are the questions the researchers asked offensive to some Havasupai?

• Do you think the researchers behaved in an ethical manner?

• What are the future consequences of the researchers’ actions?

Sampling

Populations vs. Samples

• Population– The complete set of individuals

• Characteristics are called parameters

• Sample– A subset of the population

• Characteristics are called statistics.

– In most cases we cannot study all the members of a population

Descriptive vs. Inferential

• Descriptive statistics– Summarize/organize a group of numbers from

a research study

• Inferential statistics– Draw conclusions/make inferences that go

beyond the numbers from a research study– Determine if a causal relationship exists

between the IV and DV

Some Key Concepts/Terms

• Target vs. Accessible Population

• Random sampling vs. random assignment

• Probability vs. Non-probability sampling

More key terms

• Sampling: The process of selecting a sub-set of a population on which to collect data.

• Sample: that sub-set• Sampling Unit: That from which or on

which you will collect data. • Target Population: A definable group or

aggregation of elements to which the results of the study are to be generalized

Even More Key Terms

• Accessible population: A definable group or aggregation of elements from which samples are selected.– Sampling frame: is equivalent to the accessible

population and, in fact, defines the accessible population.

• External validity.– Population Generalizability (validity): the extent to

which the results of an experiment can be generalized from the sample to the population.

– Ecological Generalizability (validity).

The Inferential Leap

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Target Population

Accessible or Operational Population

Sample

Sampling Unit

Sampling Unit

Sampling Unit

Sampling Unit

Simple Random Sampling1 092725 012157 827052 297980 625608 9641342 104460 007903 484595 868313 274221 3671813 676071 388003 266711 323324 044463 7628034 881878 862385 203886 261061 096674 8115485 534500 336348 086585 241740 581286 0084356 094276 615776 242112 985859 075388 082003

1. Andrea2. Tina3. Paul4. Wilbur5. Sandra

6. Kathy7. Jim8. George9. Emir10. Becky

11. Sharon12. Gladys13. Jose14. Bill15. Sue

16. Erica17. Aaron18. Fred19. Pam20. Roger

Stratified Random Sampling1 092725 012157 827052 297980 625608 9641342 104460 007903 484595 868313 274221 3671813 676071 388003 266711 323324 044405 7628034 881878 862308 203886 261061 096674 8115485 534500 336348 086585 241740 581286 0084356 094276 615776 242112 985859 075388 082003

1. Andrea2. Tina3. Kathy4. Sandra5. Becky

6. Paul7. Wilbur8. Jim9. George10. Emir

6. Sharon7. Gladys8. Sue9. Erica10. Pam

1. Jose2. Bill3. Aaron4. Fred5. Roger

Systematic Sampling

• Say you have a target population that has a 100,000 members.– And:

• A list is available.• You need 1,000 cases for your sample.

• 100,000/1000 = 100.– Select a random number from table.

• Then select every 100th case.

Cluster Sampling

• Naturally occurring groups.– State, district, school, classroom, student.– Randomly sample from one level then survey,

interview, etc.

• Multistage sampling.– Randomly select from one level.– Then randomly select within that level.

Convenience Sampling

• Why convenient?– Sample that is located near the researcher– Connections with administrator or staff– Researcher is familiar with the setting– Data is already available

• Shortcomings of convenience samples?

Target vs. Accessible Population

• High School Sports Officials

• Students enrolled in 5th grade in NM schools

• Albuquerque Residents

• The U.S. Electorate

• National Association of Sports Officials Membership

• APS 5th graders• Albuquerque Phone

Book• Registered Voters

Volunteers in Sampling

• How might volunteers differ?• Children having parental permission

– More academically competent– More popular with peers– More physically attractive– Less likely to smoke or use drugs– More likely to be white– More likely to come from two-parent household– More likely to be involved in extracurricular activities– Less likely to be socially withdrawn– Less likely to be aggressive

Size of the Sample

• Bigger is (usually) better.– Unless?

• How big is big? Power analysis.

• Practical issues.

• Attrition.

• Reliability.

• Cost/ benefit.

In Small Groups

• Identify your – Target population– Accessible population

• Sampling strategy– Strengths – Weaknesses