salkind ppt ch02 8e -...
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9/25/12
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© 2011 Pearson Prentice Hall, Salkind.
The Research Process: Coming to Terms
© 2011 Pearson Prentice Hall, Salkind.
} Describe the research process from formulating questions to seeking and finding solutions.
} Describe the difference between dependent and independent variables.
} Identify other types of variables that may interfere with the research process.
} Define a hypothesis and describe how it works. } Discuss the value of the null hypothesis.
© 2011 Pearson Prentice Hall, Salkind.
} Describe the differences between a null hypothesis and a research hypothesis.
} List the characteristics of a good hypothesis. } Explain the difference between a sample and
the population. } Define statistical significance and explain its
importance.
© 2011 Pearson Prentice Hall, Salkind.
} From Problem to Solution } All About Variables } Other Important Types of Variables } Hypotheses } Samples and Populations } The Concept of Significance
© 2011 Pearson Prentice Hall, Salkind. © 2011 Pearson Prentice Hall, Salkind.
Increasing our understanding of how and why we behave the way we do!!
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© 2011 Pearson Prentice Hall, Salkind.
} From Problem to Solution ◦ Noting an interesting question ◦ Stating the question in such a way that it can be
answered } The Language of Research
© 2011 Pearson Prentice Hall, Salkind.
© 2011 Pearson Prentice Hall, Salkind.
} Variables are a class of outcomes that can take on more than one value
} The more precisely a variable is measured, the more useful the measurement is
© 2011 Pearson Prentice Hall, Salkind.
} The outcomes of a research study } Depend on the experimental treatment
© 2011 Pearson Prentice Hall, Salkind.
} Treatments or conditions under control of the researcher
} Levels—at least two different values of the independent variable must be present
© 2011 Pearson Prentice Hall, Salkind.
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© 2011 Pearson Prentice Hall, Salkind.
} Independent variable is not confounded ◦ Levels do not vary systematically with other
variables } Dependent variable is sensitive to changes
in the independent variable
© 2011 Pearson Prentice Hall, Salkind.
© 2011 Pearson Prentice Hall, Salkind.
} Control Variable: Has a potential influence on the dependent variable
} Extraneous Variable: Has an unpredictable impact on the dependent variable
} Moderator Variable: Variables related to independent or dependent variables, and hiding the true relationship between independent and dependent variables
© 2011 Pearson Prentice Hall, Salkind.
Type of Variable
Definition Other Terms You Might See
Dependent A variable that is measured to see whether the treatment or manipulation of the independent variable had an effect
n Outcome variable n Results variable n Criterion variable
Independent A variable that is manipulated to examine its impact on a dependent variable
n Treatment n Factor n Predictor variable
Control A variable that is related to the dependent variable, the influence of which needs to be removed
n Restricting variable
Extraneous A variable that is related to the dependent variable or independent variable that is not part of the experiment
n Threatening variable
Moderator A variable that is related to the dependent variable or independent variable and has an impact on the dependent variable
n Interacting variable
© 2011 Pearson Prentice Hall, Salkind. © 2011 Pearson Prentice Hall, Salkind.
} Reflects the general problem under study } Restates the general problem in a form that is
precise enough to allow testing
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© 2011 Pearson Prentice Hall, Salkind.
} States that there is no relationship between the independent and dependent variables under study
} Ho: µ1 = µ2 ◦ Ho: Null hypothesis ◦ µ1: Theoretical average of population 1 ◦ µ2: Theoretical average of population 2
© 2011 Pearson Prentice Hall, Salkind.
} A starting point for analysis ◦ Accepted as true absent other information ◦ Assumes that chance caused any observed
differences
} Provides a benchmark for comparison
© 2011 Pearson Prentice Hall, Salkind.
} A statement of inequality } A relationship exists between the
independent and dependent variables
• H1: ≠ – H1: Research hypothesis – : Theoretical average of population 1 – : Theoretical average of population 2
X1
X2
X1 X2
© 2011 Pearson Prentice Hall, Salkind.
} Nondirectional Research Hypothesis ◦ Groups are different, but direction is not specified ◦ H1: ≠
} Directional Research Hypothesis ◦ Groups are different, and direction is specified ◦ H1: > ◦ H1: <
X1
X1
X2
X1
X2
X2
© 2011 Pearson Prentice Hall, Salkind.
} Directly tested during research process } To compare against null hypothesis
© 2011 Pearson Prentice Hall, Salkind.
} Null ◦ Equality between
variables ◦ Refers to population ◦ Indirectly tested ◦ Stated using Greek
symbols (µ) ◦ Implied
} Research ◦ Inequality between
variables ◦ Refers to sample ◦ Directly tested ◦ Stated using Roman
symbols ( ) ◦ Explicit
X
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© 2011 Pearson Prentice Hall, Salkind.
} Is stated in declarative form } Posits a relationship between variables } Reflects theory or literature } Is brief and to the point } Is testable
© 2011 Pearson Prentice Hall, Salkind.
© 2011 Pearson Prentice Hall, Salkind.
} The SAMPLE is a representative portion of a POPULATION
} The POPULATION is the entire group of interest
} Results from the SAMPLE should generalize to the POPULATION
© 2011 Pearson Prentice Hall, Salkind.
© 2011 Pearson Prentice Hall, Salkind.
} Observed differences (PROBABLY) result from the treatment and not from chance
} Why? ◦ Influences other than the treatment
} Significance level = risk associated with not being 100% certain that null hypothesis is incorrect
© 2011 Pearson Prentice Hall, Salkind.
} Describe the research process from formulating questions to seeking and finding solutions?
} Describe the difference between dependent and independent variables?
} Identify other types of variables that may interfere with the research process?
} Define a hypothesis and describe how it works? } Discuss the value of the null hypothesis?
9/25/12
6
© 2011 Pearson Prentice Hall, Salkind.
} Describe the differences between a null hypothesis and a research hypothesis?
} List the characteristics of a good hypothesis? } Explain the difference between a sample and
the population? } Define statistical significance and explain its
importance?
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