Research Methods in Crime and Justice

Chapter 5Causality

Establishing a Causal Relationship

• Many researchers, particularly during explanatory research, attempt to determine the cause(s) of behavior.

• Establishing a causal relationship between two variables is a difficult research challenge.

• Three requirements (standards) must be met before a causal relationship can be established.

Temporal Order

• The first causal rule is temporal order, which simply states that the cause must precede the effect.

• This is pretty logical, right? • If X is the cause of Y, then X must have

happened first.

Correlation

• The second causal rule is correlation. • When two variables are correlated they vary

together in a predictable way. • The correlation between two variables may be

positive or negative.

Types of Correlations

• If X and Y are positively correlated, then– When X increases Y also increases, or– When X decreases, Y also decreases.

• If X and Y are negatively correlated, then– When X increases, Y decreases, or– When X decreases, Y increases.

Lack of Plausible Alternative Explanations

• The final causal requirement is often the most difficult to meet.

• The lack of plausible alternative explanations requires the researcher to eliminate all other reasonable causes for the change, leaving only the variable that the researcher alleges to be the cause.

Spuriousness

• When a researcher falsely proposes a causal relationship, we say that the relationship is spurious.

• Spurious just means false. • More often than not, researchers commit this

error because they have failed to confirm one or more of the three causal rules.

Getting to the Point

• Researchers use three causal rules to determine whether a causal relationship exists between two variables. Each of these three rules must be met before a researcher can prove that one variable is the cause of another.

Getting to the Point

• The first causal rule, temporal order, requires that the cause must precede the effect.

• In other words, the variable that is alleged to be the cause of another variable must happen first.

Getting to the Point

• The second causal rule, correlation, requires that the variables in a causal relationship be related to one another, or change together.

• A change in one variable must be associated with a change in another variable.

• Correlations can be positive or negative.

Getting to the Point

• The third causal rule, lack of plausible alternative explanations, requires the researcher to eliminate all other reasonable causes before concluding that one variable causes another.

Getting to the Point

• Spuriousness refers to a false causal finding.

• It occurs when a researcher alleges a causal relationship between two variables but fails to confirm at least one of the three causal rules.

Research Methods in Crime and Justice

Chapter 5Causality