Research Methods in Crime and Justice

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. • The manner in which we describe things can sometimes help us understand a problem or phenomenon more precisely.

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 • Generally, there are three types of variables. • Independent variables • Dependent variables • Intervening variables • Each type of variable functions differently within a hypothesis.

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 • 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 • 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? • 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 • 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? • 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 • 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 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 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 • 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 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 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 • 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 • 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 • 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 • 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 • 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 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 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 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 • 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 • 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 • 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 • A variable is any characteristic of an individual, group, organization or social phenomenon that changes.

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 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 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 Point • Good research questions should be; • Measurable, • Unanswered, • Feasible, and • Disinteresting.

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 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 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 Justice Chapter 7 Variables and the Structure of Research

Research Methods in Crime and Justice