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    Experimental Design Structures

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    Answer Questions About Experimental Design

    1. Explain the difference between multiple independent variables and multiple levels of independent variables. Which is better?
    2. What is blocking and how does it reduce "noise"? What is a disadvantage of blocking?
    3. What is a factor? How can the use of factors benefit a design?
    4. Explain main effects and interaction effects.
    5. How does a covariate reduce noise?
    6. Describe and explain three trade-offs present in experiments.

    References: At least five (5) resources. In addition to these specified resources, other appropriate scholarly resources, including older articles, may be included.

    Length: 4-5 pages

    Use current APA standards.

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    Solution Preview

    Multiple independent variables are those variables that are changed or controlled in an experiment to test the effects on the dependent variable(s).
    Normally, in an experiment with a control treatment, there are two levels. These are experimental and control levels. The independent variable can have several levels. For example, an experiment can compare the attitudes of students in five different grades (1). Then the independent variable (each grade) would have 5 levels. In an experiment normally one or two independent variables are tested in an experiment. Having many independent variables makes it difficult to ascertain the influence of each upon the final results.
    It is better to have multiple levels of a single independent variable. Having several independent variables makes it difficult to determine the influence of each on the final results. It is useful to have one independent variable and several dependent variables because manipulating the independent can influence many things. These are influences are captured by the dependent variables. The rationale for having more than one independent variable in an experiment is that it allows the researcher to answer more research questions. Also, including more than one independent variables also allows the researcher to answer questions about whether the effect of one independent variable depends on the level of the other independent variables.

    Blocking, means arranging similar units in groups that are similar to one another. There is a need to eliminate the influence of extraneous factors. This is done by blocking. Blocking helps control variation among experimental units from sources that are not of interest to the researcher (2). In other words blocking helps control noise. Blocking reduces noise by ...

    Solution Summary

    The response provides you a structured explanation of experimental design . It also gives you the relevant references.