“good for” or generalizable back to the teachers in the school building or district, whichever the case may be. Depending on the overall purpose of the study and how the results of the study will be used and disseminated, lack of generalizability might not be an issue. If the purpose of the study is to use the results to make decisions at either the school building or district level, then such sampling methods are adequate.
However, if the intent of the study is to add to the academic or professional knowl-edge base on a subject by publishing on a national level, such sampling techniques would be considered a major flaw in the study design. Census sampling is an-other nonrandom sampling technique used in quantitative research. In census sam-pling, the researcher surveys the entire realistic population without drawing a random sample from the population. This technique may be used when the study has unlimited resources or the realistic population is not too large. Census sampling is frequently used by educators who are only trying to obtain data on their own school or district. Such data can be useful in learning about that particular school or district; however, remember that the results cannot be generalized to other schools or districts because the sample was not chosen randomly.
Sample Size and Survey Response Rates
Although random selection certainly plays a pivotal role in a study’s credibility, the size of the sample that one selects from the realistic population is also important.
If the sample is too small, it may not fully represent the population from which it was drawn, and therefore, the findings from the study cannot be generalized back to the wider audience, even though random sampling practices were used.
Even though there are no “hard or fast” rules for determining sample sizes, there are some general guidelines to consider when planning a study. For survey research, if the population is fewer than 200 individuals, the entire population should be sampled. This would be considered census sampling. At around a pop-ulation of 400, approximately 50% of the poppop-ulation should make up the sample, and populations over 1,000 require about 20% for an appropriate sample. For large populations of 5,000 or more, samples of 350 to 500 persons are often adequate.
For correlational studies, a minimum of 30 participants should be tested. Experi-mental research studies generally require at least 30 participants per group. These generalizations are based on the work of Krejcie and Morgan (1970), and their ar-ticle should be consulted for more precise information about sample size.
important consideration. Most professional organizations have their own codes of ethics (see the American Psychological Association and the American Sociologi-cal Association for examples). In addition, colleges, universities, and other insti-tutions that conduct research have institutional review boards (IRBs) whose members review proposals for research to determine if ethical issues have been considered. If you are conducting research in a noncollege setting, either an ele-mentary or secondary school or a community organization, there may not be a committee called an “IRB.” In this case, you will need to find out who will review your proposal and the procedures you will need to follow to obtain approval. For the most part, issues of ethics focus on establishing safeguards that will protect the rights of the participants. The traditional and often dominant issues that emerge when considering research ethics involve obtaining informed consent from par-ticipants, protecting them from harm, and ensuring confidentiality. In-formed consent means that participants have been given information about procedures and risks involved in the study and have been informed that their par-ticipation is voluntary and they have the right to withdraw from the study with-out repercussions. IRB committees typically scrutinize research proposals for these issues and will weigh any potential risk to the participants against any possible gains for science. Keep in mind that the process for addressing ethical issues might change the participants in your study. This may happen because some of the peo-ple that you have selected will not agree to be in the study or the IRB may not give you permission to use those participants. Even if you use a random sampling procedure, the final participants in your study are volunteers. All quantitative re-searchers should consider how this might change the representativeness of the sample or exclude key informants.
The members of the IRB review proposals and will examine the methods de-scribed in the proposal to ensure that all ethical considerations have been ad-dressed and that sufficient detail of the actions to be taken by the researcher are provided. As was already mentioned, most institutions whose students, professors, and staff conduct research have their own IRB committees with specific guide-lines for study approval. IRB committees are mandated by national legislation (National Research Act, Public Law 93–438). To be well versed in specific re-quirements and procedures, you should contact your own university or college’s IRB committee. IRB committees typically require that the researcher prepare a document that includes the following:
• A cover page where the researcher introduces the principal investigator and his or her qualifications and contact information, the project title, and the type of research that is being proposed.
• A detailed description of the study. This would include a summary of the literature, the research method, the significance of the research, and particulars
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about the location and duration of the study. The committee will want the specifics on any treatment (for experimental research) and any instruments or pro-tocols that might be used.
• A description of the participants. The researcher would need to include background information on the individuals in the sample and the sampling pro-cedures to be used. If the participants are to be selected from a specific institution (school, hospital, club, etc.), then written permission is needed from the director or principal.
• Discussion of inducements, benefits, or compensation to be offered to the participants. If the participants are provided any incentives to encourage their participation in the study, the specifics should be explained.
• Analysis of the risks and benefits. If there are any potential risks to the par-ticipants, the researcher would want to clearly indicate how the benefits would outweigh any risks.
• Informed consent, confidentiality, voluntary nature of the project, and de-briefing activities. A description of the procedures for obtaining informed con-sent must be described in order to obtain IRB approval. This is particularly important when children younger than 18 years are being used as participants. In this case, parental consent must be obtained. Most IRB committees require that the researcher submit copies of the informed consent forms. This consent form must include at least the following information:
Detailed description of the project Description of any potential risks involved The voluntary nature of the study
A confidentiality statement
Some educational studies might be considered IRB exempt. These are studies that involve commonly accepted educational practices and those that report the re-sults of educational tests (such as those published on Web sites). For example, new instructional practices or program evaluations commissioned by the school to re-fine ongoing practice would be exempt. You must consult your IRB committee if you believe that your study falls under this category. Some IRB committees also have expedited forms that can be used under specific circumstances. Once again, to determine the type of IRB form that is necessary for your study, you should contact your IRB committee. Most important, the IRB must be submitted and approved before any data are collected. So be sure to start this process early.
Keep in mind that the procedures outlined in one’s IRB proposal are not cast in stone, meaning that they can be modified to meet the ever-changing needs of
the researcher and the overall study and its purpose. This, in fact, is common. In many situations when researchers enter the field and start conducting their study, they find that the real-world situations vary considerably from what they had en-visioned when creating their proposal on paper. Minor changes to a proposal method typically do not require one to go back and be “reapproved” by the com-mittee or board that initially reviewed and approved the study. Some examples of these modifications might include increasing the study’s sample size or modifying items on the survey following its pilot. Because of its exploratory nature, modifi-cations are expected in qualitative research. When conducting a case study or ethnographic study, it may be necessary to submit a series of small research pro-posals to the committee, instead of one large proposal. This will allow the quali-tative researcher to start out with broad procedures when entering the research field and to maintain the ability to refine the process as the study progresses.
Ethics in Qualitative Research
Although all research studies must be approved by your institution’s IRB com-mittee, there are some unique ethical considerations surrounding qualitative re-search studies because of their emergent designs. That is, by its nature, much of what occurs in qualitative research is unknown by the researcher at the beginning of the study. Although the study does have a framework that includes likely ques-tions and observaques-tions, unanticipated issues might arise as the study proceeds.
Informed Consent. The emergent nature of qualitative research makes the task of obtaining informed consent a difficult one. Informed consent is based on the sci-entific realism framework where researchers know before a study begins what mea-sures will be used and what treatments will be given to participants. According to Eisner (1998), “the notion of informed consent implies that researchers are able to anticipate the events that will emerge in the field about which those to be ob-served are to be informed” (p. 215). This type of consent is inconsistent with most qualitative research. For example, a researcher decides to conduct a study where the interactions of middle school girls are observed and documented during their study hall periods. The participants and their parents are told that a researcher will observe the interactions that occur and will conduct a focus group interview that centers on middle school girls’ involvement in cliques. All girls and their par-ents consent to participate. During the focus group interview, the girls decide that they are going to tell Mary (one of the middle schoolers) that they do not like her and do not want her to be part of the group. Mary is devastated and embarrassed by what has occurred in the focus group interview. You might say, she, her ents, or both signed an informed consent, and that is certainly true. But what
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ent or child would agree to be part of such a study if they knew that it might re-sult in a hurtful and uncomfortable situation? Probably, not too many! In addi-tion, during the focus group, the interviewer might change or add questions (probes) to those planned in the protocol based on the responses of the group or issues raised by the participants that the researcher did not anticipate. Because of the emergent nature of the study, it may not be possible to provide full informa-tion about the methods that will be used in the study.
Protection from Harm. Protection from harm is one of the most basic of ethical concerns. It applies to both physical and emotional harm. Several issues need to be considered here. First, a qualitative research study by its nature does not impose a treatment and occurs in a naturalistic setting. As such, the researcher does not have to be concerned about whether or not he or she is doing something harm-ful to the participants or placing them in a harmharm-ful situation. However, in a qual-itative research study, the researcher, to varying degrees, becomes involved with the participants. The fact that the researcher becomes part of the group or asks certain questions could potentially influence behavior in a way that produces un-wanted or adverse consequences. For example, you are conducting a phenome-nological study that includes interviewing high school students of color about their perceptions of institutionalized racism at their school. Because of your questions, many hurtful experiences suffered by the participants are brought to the surface.
The emotional distress experienced during the interview by itself might present a source of potential harm that the researcher must consider. This might be han-dled by making sure students have a person with whom they can discuss their feel-ings. What if, however, as a result of their discussion, the students decide to mobilize and demand changes from the administration of the school? Researchers who believe strongly in the advocacy paradigm would take pride in such an out-come. Taking the scenario one step further, say that as part of the mobilization, the students get into a violent encounter with individuals who are part of the in-stitutional structure (an administrator or a teacher). In this situation, the qualita-tive investigation resulted in unanticipated harm (a violent encounter) to the participants of the study. The lesson here is that researchers must consider care-fully the actions they take with the participants and, wherever possible, provide for ways to deal with unanticipated outcomes.
Confidentiality. In general, most researchers promise confidentiality to the par-ticipants of their studies. However, can this promise always be kept? Are there sit-uations where a qualitative researcher must, or at least should, consider breaching confidentiality? Consider the following. You are a qualitative researcher who is observing an after-school program at an inner-city elementary school. One of the
staff members is unduly harsh, negative, and unfair to the young children. This staff member, along with others, has signed a consent form allowing you to con-duct observations as long as his or her confidentiality is protected. Should you in-form the principal of the school about the behavior of the after-school staff member? Is your primary responsibility to your study or your participants? Where do our loyalties lie? Obviously, this is a decision that needs to be made by the re-searcher. However, according to Lincoln and Guba (1985), the relationship that develops between the researcher and the participant should be of primary im-portance. A good qualitative study also provides substantial information on the context of the study and provides a detailed description of the group or setting studied. The extensive detail may make it difficult to keep confidential the per-sons or school being studied.
Ethical Issues in Quantitative Research
As is the case for qualitative studies, quantitative studies are also faced with unique ethical challenges. These challenges will come under scrutiny from the IRB com-mittee because in experimental and single-subject designs, researchers are at-tempting to change or influence the behavior of the participants.
Protection from Harm. The ethical obligation to protect participants from harm applies to both the treatment and control groups. Clearly, no researcher would set up a treatment that will change behavior for the worse, right? We certainly hope not. Researchers usually expect experimental treatments to improve the perfor-mance of participants, and as such, they must carefully consider the nature of the treatment. However, consider this scenario. What if a treatment is likely to pro-duce substantial benefits for the experimental group? Would it be ethical to de-prive the control group of the treatment? For example, if you have developed a teenage pregnancy prevention program that you expect will truly help prevent early sexual activity by teens, can you in good conscience deny giving this pro-gram to the control group? Many experimental studies now simply deliver the treatment to the control group after the study is completed. In these cases, the control group might be referred to as waiting-list control group. However, if the study lasts six months to a year, it may be too late for some youth! Another ap-proach is to deliver different amounts of the treatment to the different groups so that no group is completely deprived. For example, one group might get the pre-vention program one day a week and another get it two days a week.
Informed Consent. Informed consent can also be tricky in quantitative research.
Telling participants the purpose of the study in advance might change how they
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respond to the treatment or how they act during the study. If you want to see if a new video decreases teachers’ gender bias, you cannot just tell participants that your study is examining how to reduce gender bias. As soon as they hear this, they are likely to begin to change or hide any of their assumptions about gender. They also might interpret the video differently if they realize that you are trying to change their behavior. Although most researchers avoid outright deception of par-ticipants, they may give their participants general descriptions of the purpose and procedures for their study: “I am studying how teachers interact with their stu-dents,” rather than “I am studying if teachers give preferential treatment to boys or girls.” If participants are not given full information about the study, however, it is necessary to debrief them afterward by explaining the full purpose of the study. Many researchers use this as an opportunity to share the results of the study with the participants and provide information about the study’s findings.
Confidentiality. Finally, some quantitative studies, especially experimental and quasi-experimental designs, require pretesting and posttesting participants. Typi-cally, you want to be able to see if your treatment has changed the scores from the pretest to the posttest. Some of the statistical tests require you to pair up pretest and posttest scores for the participants, which presents a possible problem for con-fidentiality. In this case, you might want to assign each participant a number or code that will allow you to later link the pretest and posttest scores.
Chapter Summary
A sample is a group or individuals that a researcher uses in a study. Samples are composed of what are referred to as “participants.” Depending on the type or ap-proach of the study, a sample would be selected from a larger population in dif-ferent ways. Qualitative researchers focus on selecting participants based on a certain characteristic that they wish to investigate and are not interested in gen-eralizing their findings beyond the settings they are studying. Purposeful sampling is a common procedure used in qualitative research that identifies key informants or persons who have specific knowledge about the topic being studied. The type of purposeful sampling that a researcher may decide to use depends on the purpose of the study.
In quantitative research, samples are selected in such a way that they can be generalized back to the larger population from which they were originally drawn.
Although the researcher would like to generalize to the ideal population or widest population possible, most researchers have to settle for working with a smaller re-alistic population. Researchers use a sampling frame or list to select participants
from the realistic population. Random sampling is a technique used by quantita-tive researchers to ensure that the sample represents or “looks like” the realistic population from which it was selected. Simple random sampling is the basic method used by quantitative researchers when individuals are randomly selected.
Other methods include stratified random sampling (to ensure the representation of subgroups) and cluster random sampling (the random selection of entire groups instead of individuals). Nonrandom techniques include convenience and census sampling. In convenience sampling, a single setting such as a school district or teacher’s classroom may be selected for the quantitative study. A major limitation of convenience sampling is the lack of generalizability beyond the initial sample.
Census sampling is when the survey researcher uses the entire realistic population without randomly selecting a sample. Sample size is another important aspect of sampling. Survey research requires a sample size of approximately 50% for pop-ulations around 400; for larger poppop-ulations of 5,000 or more, a sample of 350 to 500 individuals is appropriate. Correlational studies require a sample of at least 30 individuals total. For experimental studies, a sample of 60 individuals total, 30 in the treatment group and 30 in the control group, is required. Researchers have to submit their proposals to an institutional review board for review to ensure that ethical considerations are being met and that no harm could possibly come to par-ticipants. Informed consent, protection from harm, and confidentiality are three main areas that make up the review process.
Key Concepts
purposeful sampling key informants sample population ideal population realistic population sampling frame random sampling cluster random selection convenience sampling census sampling
institutional review board
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