Conducting an Experiment

5 Key excerpts on "Conducting an Experiment"

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  eBook - PDF

  The Practical Researcher

  A Student Guide to Conducting Psychological Research

  • Dana S. Dunn(Author)
  • 2012(Publication Date)
  • Wiley-Blackwell

    (Publisher)

  164 CHAPTER OUTLINE Formulating a Testable Hypothesis Developing an Experimental Hypothesis Operational Versus Descriptive Definitions Reliability and Validity Reliability of a Measure Construct Validity Validity and Psychological Testing Closing Comments on Reliability and Validity Manipulating Independent Variables Control Groups Are Essential Special Cases: Subject Variables Error Measuring Dependent Variables Avoiding Bias Pilot Testing Demand Characteristics Experimenter Bias Sampling and Assigning Participants Sampling Issues Simple Assignment Techniques Research Design: Factor and Factorial One-Factor Designs: Posttest-Only and Pretest–Posttest 2 × 2 Designs and Beyond Other Design Options: Subject Variables Revisited Within-Subjects Designs Between and Within Factors Combined: Mixed Designs Single-Participant Experiments Conclusion: A Model of the True Experiment Experimental Research 6 165 Chapter 6: Experimental Research In many ways, the first half of this book was preparation for this chapter, in which the experimental approach to psychological research is reviewed in detail. The advantage of the experiment is clear: It allows the practical researcher to tease cause apart from effect and to effectively rule out competing explanations in favor of a sole account of some phenomenon. To get to that point, of course, the theoretical and practical sides of experimental research must be reviewed in detail, including the role of hypothesis testing, the manipulation of indepen- dent variables, the measurement of dependent variables, and the selection of an appropriate research design. A variety of exercises and suggestions accompany each of these topics, and such details add to the precision of your experiment and enhance its likelihood of success.

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  Mass Media Research

  • Roger Wimmer, Joseph Dominick(Authors)
  • 2013(Publication Date)
  • Cengage Learning EMEA

    (Publisher)

  In the sim-plest form of an experiment, researchers manipulate the independent variable and then observe the responses of subjects on the dependent variable. Although every experi-ment is different, most researchers agree that the following eight steps should be followed when Conducting an Experiment: 1 . Select the setting. Many experiments are best conducted in a laboratory or in another environment under the direct con-trol of the researcher. Others are best con-ducted in more natural surroundings where the researcher has little, if any, control over the experimental situation. This latter type of experiment is discussed in more detail later in this chapter. 2 . Select the experimental design. The appropriate design depends on the nature of the hypothesis or the research question, types of variables to be manipulated or mea-sured, availability of subjects, and amount of resources available. 3 . Operationalize the variables. In the experimental approach, independent vari-ables are usually operationalized in terms of the manipulation done to create them. Dependent variables are operationalized by constructing scales or rules for categorizing observations of behavior. 4 . Decide how to manipulate the inde-pendent variable. To manipulate the inde-pendent variable (or variables), a set of specific instructions, events, or stimuli is developed for presentation to the experimen-tal subjects. There are two types of manipu-lations: straightforward and staged. In a straightforward manipulation , writ-ten materials, verbal instructions, or other sti-muli are presented to the subjects. For example, Baran, Mok, Land, and Kang (1989) used a straightforward manipulation of their independent variable — product posi-tioning. One group of subjects was presented with a “ generic ” shopping list that contained items such as ice cream, frozen dinners, mus-tard, and coffee.

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  Laboratory Experiments in the Social Sciences

  • Murray Webster, Jane Sell(Authors)
  • 2007(Publication Date)
  • Academic Press

    (Publisher)

  I hope this chapter can help with the process of doing a real experiment. I hope also to make clear some elements of experimental design that are often overlooked in more philosophical or abstract discussions. For convenience, the steps in creating and Conducting an Experiment can be divided into several stages: designing the experiment, pretesting the operations and pilot testing the experiment, and analyzing and interpreting the data it produces. Every stage in the execution presents challenges and requires decisions on the part of the experimenters. As an overview, it is helpful to keep in mind that the essence of experimental design is to create a situation or multiple situations that include all the factors described in a theory, and only those factors. In most cases, an experiment will contrast multiple conditions, and those will ideally be identical to each other except for differences required by contrasting hypotheses. II. DESIGNING THE EXPERIMENT Good experiments begin with an explicit theory, which has the structure to permit predictions of derived consequences. Theoretically derived conse-quences are sentences telling outcomes a theory predicts, given a specified kind of situation. However, derived consequences contain abstract theoretical terms, not concrete terms that are immediately observable. For instance, a derived consequence of David Willer’s network exchange theory (NET) (Willer et al ., 2002) might be, “A person occupying a central node in a network will have more negotiating power than someone occupying an isolated node.” While the sentence’s meaning may be clear, it does not tell us in terms of operations just what being “central” means, or how to observe “power.” On the other hand, “A person with two potential exchange partners will gain more points in negotiation than someone with only one partner” translates the theoretical terms into observable facts in an experimental situation.

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  Research Methods

  A Tool for Life

  • Bernard C. Beins(Author)
  • 2017(Publication Date)
  • Cambridge University Press

    (Publisher)

  Complications arise in any research project because small details of the research situation often have effects on participants’ behaviors that we don’t anticipate or even recog- nize. Further, because an experimental session involves an interaction between people—an experimenter and a participant—social effects can contribute to changes in behavior. Nonetheless, we try to construct our research design to have maximal reliability and internal validity. We create an experimental approach that others can repeat and obtain the same pattern of results; we also put together a study whose results provide meaningful answers to our questions. CHOOSING A METHODOLOGY: THE PRACTICALITIES OF RESEARCH In psychology, the word experiment has a specific meaning. It refers to a research design in which the investigator actively manipulates and controls variables. Scientists regard experimental methods of research as the gold standard against which we compare other approaches because experiments let us determine what causes behavior, which can lead to the ultimate scien- tific goal—control. In general, researchers often prefer experiments over other methods such as surveys, observational studies, or other descriptive and correlational approaches. Experiment—A research project in which the investigator creates initially equivalent groups, systematically manipulates an inde- pendent variable, and compares the groups to see if the independent variable affected the subsequent behavior. 150 CHAPTER SIX It is important to understand the difference between an experiment and other ways of carrying out a research project because in everyday language people often refer to any data collection project as an experiment. In fact, until the middle of the 1900s, psycholo- gists, like other scientists, referred to any research project as an experiment. Since then, however, psychologists have used the term in a specific way.

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  Social Science Experiments

  A Hands-on Introduction

  • Donald P. Green(Author)
  • 2022(Publication Date)
  • Cambridge University Press

    (Publisher)

  3 Conducting a Practice Experiment (Not Involving Human Subjects) The purpose of this chapter is to give readers a feel for how experiments are designed, implemented, and analyzed. The chapter walks through the steps of designing a small, inexpensive experiment that can be conducted at home. We will also discuss the fine points of implementing an experiment, assembling a dataset, and preparing a statistical analysis. In order to put aside ethical issues that apply to experiments involving human participants, this chapter confines its attention to product testing. Drawing inspiration from the first field experiments conducted a century ago, my running example will test the effects of fertilizer on plant growth (Fisher 1926). 1 I will walk through my reasoning as I design the experiment to help you design your own experiment. Later in the chapter, I describe some illustrative experiments conducted by students on topics such as cooking, the preservation of carved pumpkins, and evoking video recommendations from YouTube. These students have generously provided their data, planning docu- ments, and R code so that you can retrace their steps. .       Think about comparing two states of the world, one that involves some kind of intervention and the other without it. How different would the outcomes be, on average, with or without the intervention? Start by posing a research question that a randomized experiment can answer. For example, one could ask, “How much larger do plants grow on average when this fertilizer and water solution is applied instead of an equivalent amount of water alone?” Framing the question in this way sets up a comparison between treatment (fertilizer plus water) versus control (just water). What kinds of questions are not well suited to randomized experimentation? One category includes questions that focus solely on describing outcomes, with no compari- son of treatment and control.

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