Although there are many theories that are evaluated, only some of them are considered good theories based on certain evaluation criteria being met. To be considered a good theory there are several evaluation criteria that must be met such as logical coherence, testability and empirical validity. Logical coherence has two elements, scope and parsimony, both of which are related. The scope of a theory refers to the range of explanations (Akers & Sellers, 2013, p. 5). If the scope of a theory is limited, then the theory itself is limited. For example, if a theory focuses only on one crime rather than several crimes, the scope of the theory may be limited. In addition to scope, parsimony refers to “using the fewest possible concepts and propositions to explain the widest range of phenomena” (Akers & Sellers, 2013, p. 5). Sparingly, it must be simple, but sufficient. An example of a theory with logical coherence is deterrence theory. Logical coherence is applicable to the theory because it recognizes that all crimes carry a threat/risk of punishment leading to deterrence in committing crimes. As a result, the theory is simple, but it also covers a wide range of phenomena, like all crimes, encompassing both broad scope and parsimony. In addition to logical coherence, testability is an important element when evaluating a theory. According to Akers & Sellers (2013), “a theory must be testable by objective and repeatable tests” (p.5); therefore, if the theory is not testable, it has no scientific value. There are several reasons why a theory might not be testable; such as its concepts may not be observable or reportable events and tautology. Tautology refers to a statement or hypothesis that is t...... middle of the card ......ed by a criminal (X) makes such events more likely to occur by continuing that style of life (Y). In addition to theories of causation, the quality of empirical testing is important. A theory that does not correctly measure the independent and dependent variables could result in inadequate methodological quality. Additionally, it may cause problems with assumptions. Furthermore, if the theory does not collect sufficient data from a related, large, and diverse sample, then it is insufficient. All these pieces are interrelated to contribute to a sufficient empirical test. For example, if a theory suggests that all men raised in a violent household will commit violent acts in the future, but does not collect data from a large enough population or does not include women in the study, their empirical tests may be meaningless, which would so that the theory is not empirically valid.