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Term of the Month

Defining Criminal Justice Research

Welcome to NIJ’s Term of the Month. Each month we are featuring a term from our scientific research portfolios informing significant American justice system issues and solutions.

November 2022 - Black Box Study

Black box studies have inputs and outputs, and although the specific constitution and structure of the system are not considered, the system's overall behavior is accounted for.

A black box study design can be used to measure the overall behavior of a complex system. It disregards the internal processes and simply measures how the final output changes depending on the input. Black box testing has long been used to study complex systems in software engineering, physics, and psychology.

In the forensic sciences, researchers use black box studies to measure the accuracy and reliability of forensic disciplines as they are currently practiced. This includes latent fingerprint examination, bloodstain pattern analysis, forensic firearms examination, and others. These disciplines largely depend on subjective comparison of evidence by human experts. The researcher uses a set of samples with known “ground truth” and treats the examiner as a black box, measuring how often their conclusions are right or wrong. This is important information for the courts to consider when deciding whether to admit forensic testimony.

Conversely, a “white box” study — in the context of forensic science — looks at the details of the examiner’s thought process or methodology to determine which factors have the most effect on the outcome. It allows the researcher to look inside the black box and gain insight into how and why examiners reach their conclusions.

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Date Created: January 28, 2021