Nomothetic offender profiles are best described by (Turvey, 2011) as offender characteristics developed by studying groups of offenders. Nomothetic profiles do not represent actual offenders that exist in the real world. They represent varying degrees of theory and possibility.
The study of nomothetic profiles focuses in observations about the characteristics of groups, which are useful and necessary when trying to define groups, solve group related problems or generate initial theories about issues in specific cases. The nomothetic offender profiles no other than the characteristics created by studying groups of offenders. Furthermore nomothetic profiles are just hypothetical. This means that nomothetic profile does not represent varying degrees of theory and possibility. These profiles use methods and approaches that help build knowledge about different categories of crime and groups of criminals. (Turvey, 2011)
The primary goal of nomothetic criminal profiling studies is to gather general, typical, common, or averaged characteristics of offender groups. These characteristics are hypothetical in the way that they do not necessarily exist in each individual case; they actually represent the theoretically possible and the probable. Problems arise when nomothetic methods are used inappropriately to make overly confident inferences or conclusive interpretations about individual offenders. In other words, when an abundance of nomothetic knowledge is applied to answer narrow idiographic questions(Turvey, 2011).
Profiling itself is a nomothetic approach in the manner that it tries to make general predictions about offenders based on the bundle of data gathered from previous offenders. Nomothetic refers to the search for general principles, relationships, and patterns by examining and combining data from many individuals. Research psychology is largely nomothetic
Using nomothetic profiles is useful in identifying patterns in mass murderer incidents. Just like (Turvey, 2011) explained with the phone box example, you study a large group of mass murder offenders and write and compare all characteristics that appear to be similar and examine the features. Using the information obtain from the group studied, you can accurately theorize about the likely characteristics of a future offender and generate probabilities of what their next move or patterns may be.
References:
Turvey, B. (2011). Nomothetic methods of criminal profiling. In Criminal profiling: An introduction to behavioral evidence analysis (3rd ed., pp. 78-80). San Diego, Calif.: Academic Press.