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Experimental Research

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Presentation on theme: "Experimental Research"— Presentation transcript:

1 Experimental Research

2 Overview of Experimental Research
Traditional type of research Purpose is to investigate cause-and-effect relationships among variables Experimental groups vs. control groups Each group of participants receives a different treatment Always involves manipulation of the independent variable Answers the question “What will be?”

3 Systematic Procedures
More than any other type of research, experimental research should follow a definite, orderly procedure Specific steps follow . . .

4 Research Validity Internal Validity – the validity of findings with the research study; the technical soundness of a study, particularly concerned with the control of extraneous influences that might effect the outcome External Validity – the degree to which the findings can be inferred to the population of interest or to other populations or settings; the generalizability of the results Both are important in a study but they are frequently at odds with one another in planning and designing a study Internal validity is considered the basic minimum for experimental research

5 What is an experimental design?
An experiment is a process or study that results in the collection of data. Usually the experiment is designed by researchers who can manipulate the conditions of the experiment and can control the factors that are irrelevant to the research objectives.

6 Parts of an experimental design
Experimental designs must first have a problem or a question that can be testable and data can be collected. Experiments must have variability and validity. (McMillan & Wergin pp.61-62, 2010) The researcher often has a hypothesis such as an “if” question; (E. C. Scott, 2004) “If skin cancer is related to ultraviolet light, then people with a high exposure to UV-light will have a higher rates of skin cancer.”

7 Key Components of Experimental Design
Once the researcher has the hypothesis then he/she must form an experiment that has the following: Independent variable Dependent variable Control group or constant Results Conclusion based on the results These are the main parts but an experiment is not limited to these few.

8 Terms Defined Hypothesis: is a proposition or a theory that one is trying to verify, in this case through experiment. Independent Variable: the variable in an experiment that can be changed or manipulated (input or causes). This can also be what is tested to see if it is the cause of the expected effect. Dependent Variable: the variable in an experiment that is being measured (output or effect) and is dependent upon the other variables. Hypothesis: An example of an hypothesis might be: "Students study more effectively in quiet than in noisy environments.“ Independent Variable: for example the independent variable is the variable that you (experimenter) has control over and can chose and manipulate for example the level of noise in the environment for the experimental and controlled group. Dependent Variable:. For example the reaction/outcome that the experimental and controlled group has to the independent variable.

9 Terms Defined cont… Experimental Group and Control Group: the experimental group is the group that receives the treatment and the control group is the group that does not receive the treatment. Error Variable: are the variables that are not controlled like the independent variable that can cause effects in the depend variable. Results: the outcome of the experiment that was performed on the groups. Experimental group and Control Group: for example, the experimental group would be the group that worked in a quiet environment and the controlled group would work in a noisy environment. Error Variable: for example,  such as the time of day, the mood of the subject, recent news events, or the weather, might also affect outcomes in an experiment.  Results: for example, the experimental group that worked in the quiet environment had a 90% better grade than the controlled group that worked in the noisy environment

10 Evaluation Criteria for Experimental Design
According to McMillian and Wergin, there nine specific criteria for evaluating experimental studies:

11 General Purpose of Study McMillan, J.H, & Wergin, J.F. (2010)
The purpose of the study is clear and concise. The research material gathered from the study will contribute to specific interpretations

12 The Research Connection McMillan, J.H, & Wergin, J.F. (2010)
The research should suggest a relationship between other studies to the most current study. The current research corresponds to other similar studies.

13 Research Method Clear and Concise McMillan, J.H, & Wergin, J.F. (2010)
The hypothesis (educated guess) is clearly stated.

14 How Was the Method Sampled? McMillan, J.H, & Wergin, J.F. (2010)
The research method sample should be documented and described in depth.

15 What Are the Variables? McMillan, J.H, & Wergin, J.F. (2010)
The variables should be defined.

16 Define Data Collection Procedures McMillan, J.H, & Wergin, J.F. (2010)
What types of data collection was used?

17 Internal and External Validity McMillan, J.H, & Wergin, J.F. (2010)
All possible external and internal factors are reviewed

18 Limitations of the Study McMillan, J.H, & Wergin, J.F. (2010)
The study draws specific conclusions and implications and also describes limitations in the study that may effect specific outcomes.

19 The Findings Can Be Generalized McMillan, J.H, & Wergin, J.F. (2010)
The findings address an approach to generalize the research procedures.

20 Your turn! Read to following experiment and see if you can identify the main components of experimental design.

21 A researcher is curious to find out what effect classical music has on people’s level of relaxation (as measured by heart rate). He suspects that listening to classical music will make people feel more calm and relaxed. He lets one group listen to classical music for one hour. He lets another group sit in a quiet room for one hour (i.e. they hear no music). After one hour, he monitors the heart rate of each participant to measure their level of relaxation.

22 What are… Independent variable: Dependent variable:
Experimental group: Control group:


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