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Chapter 2

The Research Process: Coming to Terms

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CHAPTER OBJECTIVES -

STUDENTS SHOULD BE ABLE TO:

� 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.

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OBJECTIVES, CONTINUED -

STUDENTS SHOULD BE ABLE TO:

� 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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CHAPTER OVERVIEW

� From Problem to Solution

� All About Variables

� Other Important Types of Variables

� Hypotheses

� Samples and Populations

� The Concept of Significance

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WHAT IS RESEARCH

ALL ABOUT, ANYWAY?

Increasing our understanding of how and why we behave the way we do!!

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THE RESEARCH PROCESS:

COMING TO TERMS

� From Problem to Solution

� Noting an interesting question

� Stating the question in such a way that it can be

answered

� The Language of Research

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VARIABLES

� 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

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INDEPENDENT VARIABLES

� Treatments or conditions under control of the researcher

� Levels—at least two different values of the independent variable must be present

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DEPENDENT VARIABLES

� The outcomes of a research study

� Depend on the experimental treatment

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THE RELATIONSHIP BETWEEN

INDEPENDENT AND DEPENDENT

VARIABLES:

WHAT MAKES GOOD VARIABLES?

� Independent variable is not confounded� Levels do not vary systematically with other

variables

� Dependent variable is sensitive to changes in the independent variable

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VARIABLES—A SUMMARYType of Variable

Definition Other Terms You Might See

DependentA variable that is measured to see whether the treatment or manipulation of the independent variable had an effect

� Outcome variable

� Results variable

� Criterion variable

IndependentA variable that is manipulated to examine its impact on a dependent variable

� Treatment

� Factor

� Predictor variable

ControlA variable that is related to the dependent variable, the influence of which needs to be removed

� Restricting variable

ExtraneousA variable that is related to the dependent variable or independent variable that is not part of the experiment

� Threatening variable

ModeratorA variable that is related to the dependent variable or independent variable and has an impact on the dependent variable

� Interacting variable

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HYPOTHESIS

� Reflects the general problem under study

� Restates the general problem in a form that is precise enough to allow testing

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NULL HYPOTHESIS

� 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

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PURPOSE OF NULL HYPOTHESIS

� A starting point for analysis

� Accepted as true absent other information

� Assumes that chance caused any observed

differences

� Provides a benchmark for comparison

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THE RESEARCH HYPOTHESIS

� 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

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DIRECTIONAL VS.

NONDIRECTIONAL RESEARCH

HYPOTHESES

� 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

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PURPOSE OF RESEARCH

HYPOTHESIS

� Directly tested during research process

� To compare against null hypothesis

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� Research

� Inequality between variables

� Refers to sample

� Directly tested

� Stated using Roman symbols ( )

� Explicit

DIFFERENCES BETWEEN

NULL AND RESEARCH

HYPOTHESES

� Null

� Equality between variables

� Refers to population

� Indirectly tested

� Stated using Greek symbols (µ)

� Implied

X

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WHAT MAKES A GOOD

HYPOTHESIS?

� Is stated in declarative form

� Posits a relationship between variables

� Reflects theory or literature

� Is brief and to the point

� Is testable

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SAMPLES AND POPULATIONS

� SAMPLE - is a representative portion of a POPULATION

� POPULATION - is the entire group of interest

� Generalizability - Results from the SAMPLE should generalize to the POPULATION

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SIGNIFICANCE

� 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