Data Literacy Series: Disparity vs. Disproportionality

Though “disparity” and “disproportionality” are often used interchangeably in discussions around social justice, policy reform, and data-driven decision-making, they have distinct meanings and implications when analyzing data and addressing systemic inequities. Understanding these two concepts’ differences is critical for developing accurate insights and solutions.

In short, disparity refers to a state of being unequal, while disproportionality refers to a state of being out of proportion. Both terms are commonly used to describe social or economic conditions, particularly concerning race and ethnicity.

What is Disparity?

Disparity refers to differences between groups that can be identified through statistical analysis. These differences could exist in many areas—access to healthcare, educational outcomes, employment rates, or incarceration rates. Disparities highlight the existence of unequal outcomes between groups, but they do not by themselves explain why these differences occur.

In the context of criminal justice, the disparity between racial or ethnic groups can be stark. For example, if a county’s data shows that out of 1,000 Black and 1,000 White individuals involved in illegal activity, 500 Black people are arrested compared to 250 White people, that reveals a racial disparity.

However, disparity does not assign a cause or address whether this gap results from systemic factors, or something else.

Simply acknowledging this disparity is not enough. To tackle an issue effectively, we must delve deeper into the contributing factors and structural forces that lead to these uneven outcomes.

What is Disproportionality?

Disproportionality, on the other hand, occurs when a group’s representation in a particular area or system is significantly higher or lower than its representation in the overall population. Unlike disparity, which focuses on differences in outcomes, disproportionality focuses on the relationship between a group’s presence in a given system compared to its prevalence in the broader population.

Consider Washington State’s Institute for Public Policy report, which reveals that while Blacks make up 12% of the U.S. adult population, they make up 33% of the U.S. prison population.  It also reveals that Whites, who make up 64% of the U.S. adult population, make up just 30% of the U.S. prison population. This report provides evidence of how different racial groups are disproportionately affected by specific policies. 

Because disproportionality indicates the overrepresentation or underrepresentation of a racial or ethnic group compared to its percentage in the total population, it can signal the need to investigate whether biased policies or practices are contributing factors.

Grasping the difference between disparity and disproportionality is crucial for anyone seeking to understand and address inequities within systems. Disparities show us where there are differences in outcomes across groups, while disproportionality reveals the over- or under-representation relative to the overall population. Understanding the difference between these two terms is important because they highlight distinct issues related to fairness, equality, and systemic challenges. 

Recognizing whether an issue is a disparity (difference in outcomes) or disproportionality (imbalance in representation) can help tailor specific interventions. For example, reducing disparities might involve addressing resource gaps, while tackling disproportionality could require systemic policy changes or bias mitigation.

Only by recognizing and analyzing both can we develop comprehensive strategies that promote fairness and equality across sectors.

Measures for Justice provides easily accessible county-level data via Commons. We encourage you to check out the live data we have by viewing Commons and exploring the data trends.