Sampling and Ethics in Psychological Research: A Comprehensive Guide - Prof. Kevin Oneil, Papers of Psychology

Download Sampling and Ethics in Psychological Research: A Comprehensive Guide - Prof. Kevin Oneil and more Papers Psychology in PDF only on Docsity! 1 Research Participants, Ethics & Writing PSY 3213 7/14/2008 Overview • Material to learn (before 7/23): – Sampling – Measurement – Experimental Design • Stuff to do for final paper (before 7/28): – Library research – Decide on sampling method, measurement & design Populations and Samples Ø “Who will be in the study?” ØGoal is to have a sample that represents the target population, which allows you to apply the results obtained from a sample to the population • Generalization is the ability to apply findings from a sample to the population • Population – Large group including all potential subjects • Sample – Small subgroup of subjects chosen from the population – May need to define a subpopulation for study Stages of Selection/Sampling • Target Population – defining people/animals we want to study • Sampling Frame – “best list” we can get of population members • Selected Sample – sampling frame members who are selected to participate in the research • Data Sample – participants from whom useful data are collected Selection/Sampling Procedures • Psychologists have devised many different ways of “acquiring” participants, but all involve three choices… – Population vs. Purposive Sampling Frame – Researcher selected vs. Self-selected – Simple Sampling vs. Stratified Sampling • … so any form of participant sampling/ selection can be identified as one of the (eight) combinations of these three choices Population vs. Purposive Sampling Frame • A “sampling frame” is the list of members of the target population the researcher starts with – Sometimes it isn’t a paper list, but a way of contacting everybody • A “population” sampling frame includes the entire population – Consider how unlikely this is … • A “purposive” sampling frame includes a subset of the entire population that is deemed “representative” of the entire population – Nearly all sampling is purposive -- getting full population list is difficult/impossible, expensive, and not necessarily better than a properly chosen purposive list 2 Researcher selected vs. Self- selected • Researcher selected -- potential participants from the sampling frame are selected by the researcher (almost always randomly), individually contacted and requested to participate in the research. • Self-selected -- all potential participants from the sampling frame are informed about the “opportunity” to participate in the research and contact the researcher if they wish to volunteer. – Assumes that the volunteers will be a “representative sample” of the target population Simple vs. Stratified Sampling • In “simple” sampling every member of the sampling frame has an equal probability of being in the study – E.g., every name on list has the same probability of being chosen • “Stratified” sampling is a bit more involved … – Divide the sampling frame into “strata” using one or more variables (e.g., age, gender, job) – Members within each strata have an equal probability of being in the study – Results in either same number of each strata/group in the sample or proportionate number (“Proportionate Sampling”) So, there are 8 combinations of ways we obtain our participants... Simple Stratified sampling sampling Simple Stratified sampling sampling Researcher- selected Self -selected Population sampling Purposive sampling frame frame * what “random sampling” means in textbooks * * ^ how “random sampling” is usually done (e.g., Gallup polls) ^ ^ + how “participant selection” is usually done in empirical research + + Textbook Terms • Random sample: A sample in which every member of the population has an equal chance of being chosen – Ideal that is not often met • Nonrandom sample: A sample from a specialized population (e.g., college students) Textbook Terms • Cluster Sampling – Used when populations are very large – The unit of sampling is a group (e.g., a class in a school) rather than individuals – Groups are randomly sampled from the population (e.g., ten classes from a particular school) • Multistage Sampling – Variant of cluster sampling – First, identify large clusters (e.g., school districts) and randomly sample from that population – Second, sample individuals from randomly selected clusters Data Sample • Not all participants will provide valid data – They might refuse to participate when invited – They might start to participate but later withdraw -- called attrition, drop-out or “experimental mortality” – They might not give valid responses 5 Ethics • History: Bad stuff • Belmont Report (1979) – Respect for persons • Participants are autonomous persons capable of making their own decisions • Persons with diminished autonomy or capacity deserve protection • Obtain informed consent • Respect privacy • Employ special protections (for prisoners, children, mentally ill, elderly, etc.) Ethics • Belmont Report (1979) – Beneficence • Do no harm to participants • Maximize benefits & minimize harm • Minimize risk of harm (no more than encountered in everyday life) • Benefits should outweigh risks • Maintain confidentiality Ethics • Belmont Report (1979) – Justice • Divide burdens of research equally between researcher & participant • Divide burdens equally across participant groups • Avoid exploiting vulnerable groups (students?) • Justify selecting only certain groups (by gender, race, etc.) IRB • Institutional Review Board – If you are affiliated with a institution that receives federal funding, research must be screened & approved by an IRB – Is a body of faculty & community members, representing many fields & many backgrounds. Informed Consent • Required of all studies, unless participant is not identifiable & put at no more than minimal risk (roughly) • Needs: – Statement of purpose – Procedures to be used; how long – Benefits & Risks – Compensation – Promise of confidentiality – Ability to withdraw without penalty – Contact information What is research? • “…a systematic investigation, including research development, testing and evaluation, designed to develop or contribute to generalizableknowledge. ” • “The human participant is a living individual about whom a researcher obtains either: (1) data through intervention or interaction with the individual; or (2) identifiable private information.” 6 Prior Research • Hypotheses (and whole studies) must be formed in light of existing research – There is going to be prior research relevant to your study • How much depends on your variables • Prior research must be described before you propose why your new research is needed “Need” for Research • Research is “needed” if: – Variable has never been investigated before • Even if nothing directly relevant, there will be analogous research. • Why is your variable important? Why might your variable have an effect? • Find research relevant to WHY the variable is important. “Need” for Research • Research is “needed” if: – Variable has been investigated before, but… • Something was done wrong • OK, fix it “Need” for Research • Research is “needed” if: – Variable has been investigated before, but… • Not in all contexts – Extend research to a new population or a new situation – Example: Research shows that undergraduate mock jurors are more likely to convict male defendants than female defendants in sexual harassment cases. – Proposal: Are non-student mock jurors more likely to convict male defendants in sexual harassment cases? – Proposal: Are undergraduate mock jurors more likely to convict male defendants in rape cases? – Why is the new context, population, or situation important? “Need” for Research • Research is “needed” if: – Variable has been investigated before, but… • Not all comparisons made – Example: Research shows that jurors convict more often when they receive DNA evidence. Other research shows that jurors convict more often when they hear eyewitness testimony. – Proposal: Does the presence of DNA evidence change how jurors react to eyewitness evidence? » (Note, the statistics for this comparison would be a bit more complex than normal) 7 “Need” for Research • Research is “needed” if: – Variable has been investigated before, but… • Inconsistent results – But why is another study going to solve the debate? – Example: Some research shows that racist jurors are more likely to convict in cases with White victims. Other research shows that racism is not related to verdicts in cases with Black victims. – Proposal: Does victim race influence whether racism is related to verdicts? – Key is to propose an explanation for the inconsistency. “Need” for Research • Research is “needed” if: – Variable has been investigated before, but… • New combination of prior results is possible. – Combine 2 variables in 1 study for first time » Example: Prior research shows that, in death penalty cases, jurors are more likely to sentence a defendant to death if he commits a heinous, brutal crime. Other research shows jurors are less likely to sentence a defendant to death if he is mentally ill. » Proposal: How do mental illness and heinousness combine to influence jurors’ sentencing verdicts? – Why are the two important to consider together? “Need” for Research • Research is “needed” if: – Variable has never been investigated before – Variable has been investigated before, but… • Something was done wrong • Not in all contexts (new situation, new population) • Not all comparisons made • Inconsistent results • New combination of prior results is possible. Reading Articles • When reading, consider: 1. What had the researchers read that prompted the research? (What relevant research exists?) 2. What was the purpose of this study? 3. What was the specific research question or research hypothesis? 4. How was the research conducted? a. Who were the participants of the study? b. Was an experimental or non-experimental design used? c. What stimulus materials were used? d. What was the independent variable? 5. What was the major finding of the study? How did the authors interpret or explain these results? 6. How did the authors integrate the results with the previous literature they reviewed? Reading an Article • Focus on the What and the Why • Introduction & Literature Review: – Why is the topic important? – What other prior research articles exist? • What did those articles find? • Why did those effects happen? • Results & Discussion – What effect did the article find (or not find)? – Why is that effect found (or not found)?