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Research Methods in Crime and Justice. Chapter 7 Variables and the Structure of Research. Variables and Hypotheses. In social science, we use variables to describe the different characteristics of individuals, groups, organizations and social phenomena.

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research methods in crime and justice

Research Methods in Crime and Justice

Chapter 7

Variables and the Structure of Research

variables and hypotheses
Variables and Hypotheses
  • In social science, we use variables to describe the different characteristics of individuals, groups, organizations and social phenomena.
  • The manner in which we describe things can sometimes help us understand a problem or phenomenon more precisely.
variables and hypotheses1
Variables and Hypotheses
  • A variable is any characteristic of an individual, group, organization or social phenomenon that changes.
  • A hypothesis is a statement that predicts how a change in one or more variables will cause a change in another variable.
types of variables
Types of Variables
  • Generally, there are three types of variables.
    • Independent variables
    • Dependent variables
    • Intervening variables
  • Each type of variable functions differently within a hypothesis.
independent variables
Independent Variables
  • An independent variable is;
    • the causal variable, or
    • the variable that a researcher predicts will be the cause of a change in another variable.
dependent variables
Dependent Variables
  • A dependent variable is;
    • the effect, or
    • the variable that a researcher predicts will change as a result of a change in another variable or set of variables.
independent vs dependent
Independent vs. Dependent
  • An easy way to distinguish between the independent and dependent variables is to ask which happens first.
  • The independent variable always happens first.
  • The first causal rule (temporal order) requires that the cause (independent variable) must happen prior to the effect (dependent variable).
independent or dependent
Independent or Dependent?
  • Children who experience domestic abuse are more likely as adults to abuse their domestic partners.
    • Independent variable – Children who experience domestic abuse.
    • Dependent variable – domestic abusive behavior as an adult.
intervening variables
Intervening Variables
  • An intervening variable is any variable that
    • occurs between the independent and dependent variables, and
    • may change how, or even if, the independent variable affects a dependent variable.
  • In other words, intervening variables intervene in the causal relationship.
independent dependent or intervening
Independent, Dependent or Intervening?
  • Children who experience domestic abuse are more likely as adults to abuse their domestic partners, unless they develop strong attachments to non-abusive adults.
    • Independent variable – Children who experience domestic abuse.
    • Dependent variable – domestic abusive behavior as an adult.
    • Intervening variable – strong attachments to non-abusive adults.
variable attributes
Variable Attributes
  • Attributes are the different characteristics or values that a variable can take on.
  • A variable’s attributes must be both;
    • Exhaustive
    • Mutually exclusive
exhaustiveness
Exhaustiveness
  • Exhaustiveness refers to the completeness of the list of attributes.
  • All of the possible attributes for each variable must be included.
  • In some cases it may be necessary to include an ‘other’ in the list of attributes.
mutual exclusivity
Mutual Exclusivity
  • Mutual exclusivity requires that the list of attributes must be we mean that each attribute must be distinctive, such that a respondent can pick one, and only one, option.
elements of a good research question
Elements of a Good Research Question
  • A research question is an interrogative statement.
    • An actual question
    • Not a statement
  • There are four criteria of a good research question.
    • Measurable
    • Unanswered
    • Feasible
    • Disinteresting
elements of a good research question1
Elements of a Good Research Question
  • Research questions should be measurable.
    • The concepts in the question should be measurable, either quantitatively or qualitatively.
    • Avoid the use of ambiguous terms and superlatives.
  • Research questions should be unanswered.
    • Most questions in the social sciences have been asked and answered by other researchers.
    • This does not mean that we cannot ask them again or in different ways.
elements of a good research question2
Elements of a Good Research Question
  • Research questions should be feasible.
    • Money and time are always finite resources.
    • Researchers should consider whether a particular research project is practical or feasible.
  • Research questions should be disinteresting.
    • Researchers should be indifferent to the outcome of their research.
    • Researchers never should try to prove anything, but be led by the evidence to the most logical conclusion.
hypotheses in social research
Hypotheses in Social Research
  • A hypothesis is a predictive statement that alleges a plausible connection between two or more variables.
    • ‘Predictive’ means the hypothesis makes a specific prediction about how two or more variables are connected.
    • ‘Plausible connection’ means that the hypothesis must describe the nature of the connection between the variables.
  • All hypotheses contain two or more variables.
the alternative hypotheses
The Alternative Hypotheses
  • An alternative hypothesis (Ha) is a predictive statement alleging a plausible connection between two or more variables.
    • This is the hypothesis the researcher wants to confirm as true at the end of the research.
    • For each alternative hypothesis the researcher must develop a competing null hypothesis.
the null hypothesis
The Null Hypothesis
  • A null hypothesis (Ho) is a predictive statement that alleges no plausible connection between two or more variables.
    • The null hypothesis is the exact opposite of the alternative hypothesis.
competing hypotheses
Competing Hypotheses
  • Alternative hypothesis (Ha): Poor academic performance in the early elementary school years is positively related to juvenile delinquency in the adolescent years.
  • Null hypothesis (Ho): Poor academic performance in the early elementary school years is not related to juvenile delinquency in the adolescent years.
the structure of research
The Structure of Research
  • In this research project the researcher wants to prove that the alternative hypothesis is a true statement.
  • Before doing so, the researcher must first prove that the null hypothesis is a false statement.
the structure of research1
The Structure of Research
  • If, the data lead the researcher to the conclusion that;
    • Poor academic performance in the early elementary school years is not related to juvenile delinquency in the adolescent years (i.e. the null hypothesis).
  • Then the researcher will accept the null hypothesis and reject the alternative hypothesis.
the structure of research2
The Structure of Research
  • If on the other, hand the data lead the researcher to the conclusion that;
    • Poor academic performance in the early elementary school years is not related to juvenile delinquency in the adolescent years (i.e. the null hypothesis).
  • Is a false statement.
  • Then, the researcher will reject the null hypothesis and accept the alternative hypothesis.
why so formal
Why so Formal?
  • Why not just ignore the null hypothesis and try to prove the alternative hypothesis?
  • Just as the criminal justice system must presume innocence, so, too, must a researcher presume no relationship between the variables in a research project.
  • The formal structure of research is intended to insure the quality of research findings.
other types of hypotheses
Other Types of Hypotheses
  • Separate from the distinction between the null and alternative hypotheses, a hypothesis can also be categorized into one of two types.
    • A hypothesis of association
    • A hypothesis of difference
  • This distinction is important because it determines how the researcher will analyze the data.
the hypothesis of association
The Hypothesis of Association
  • A hypothesis of association alleges that a change in the independent variable(s) is associated with a change in the dependent variable.
    • In most cases the independent variable in a hypothesis of association will be measured at the ordinal, interval or ratio level of measurement.
    • Hence, the data used to test a hypothesis of association can be illustrated in a linear graph.
the hypothesis of difference
The Hypothesis of Difference
  • A hypotheses of difference alleges that the independent variable(s) makes groups different with respect to the dependent variable.
    • In most cases the independent variable in a hypothesis of difference will be measured at the nominal level of measurement.
    • Hence, the data used to test a hypothesis of difference can be illustrated in a bar graph.
getting to the point
Getting to the Point
  • A variable is any characteristic of an individual, group, organization or social phenomenon that changes.
getting to the point1
Getting to the Point
  • An independent variable is the causal variable, or the variable that a researcher predicts will be the cause of a change in another variable.
  • A dependent variable is the effect, or the variable that a researcher predicts will change as a result of a change in another variable or set of variables.
getting to the point2
Getting to the Point
  • An intervening variable is any variable that occurs between the independent and dependent variables, changing how, or even if, the independent variable affects a dependent variable.
getting to the point3
Getting to the Point
  • Attributes are the different characteristics or values that a variable can take on.
  • Exhaustiveness refers to the completeness of the list of a variable’s attributes.
  • Mutual exclusivity refers to the capacity for a list of attributes to provide one, and only one, option for each respondent
getting to the point4
Getting to the Point
  • Good research questions should be;
    • Measurable,
    • Unanswered,
    • Feasible, and
    • Disinteresting.
getting to the point5
Getting to the Point
  • A hypothesis is a statement that predicts how a change in one or more variables will cause a change in another variable.
  • An alternative hypothesis is a predictive statement that alleges a plausible connection between two or more variables.
  • A null hypothesis is a statement that alleges no plausible connection between two or more variables.
getting to the point6
Getting to the Point
  • A hypothesis of association alleges that a change in the independent variable(s) is associated with a change in the dependent variable.
    • If the independent variable is ordinal, interval or ratio, the hypothesis will be one of association.
    • Hence, the data used to test a hypothesis of association can be illustrated in a linear graph.
getting to the point7
Getting to the Point
  • A hypothesis of difference alleges that the independent variable(s) makes groups different with respect to the dependent variable.
    • If the independent variable is nominal, the hypothesis will be one of difference.
    • Hence, the data used to test a hypothesis of difference can be illustrated in a bar graph.
research methods in crime and justice1

Research Methods in Crime and Justice

Chapter 7

Variables and the Structure of Research