Why Police Leaders Need Better Crime Charts

Estimated reading time: 9 minutes

It’s CompStat day. The room is filled with patrol maps, charts, and coffee cups. The analyst walks through the latest numbers, percent change charts showing crime up here, down there, and a bright kernel density map lighting up half the city.

The captain nods, scanning the visuals, trying to make sense of where to focus limited resources next. The discussion turns to whether recent changes are real trends or just the usual week-to-week fluctuation.

If you’ve been in that meeting, as an analyst or command staff, you know the challenge isn’t disagreement. It’s interpretation. The data is there, but the visuals don’t always tell the story clearly. Sometimes what looks like a “crime spike” is just normal variation. And sometimes the map that seems to show that half the city is “hot” actually hides the few streets that really matter.

The Power (and Problem) of Data Visualization in Policing

Since the early days of CompStat, policing has depended on data to guide decision-making such as where to patrol, how to allocate resources, and how to measure success. Today’s dashboards and maps are more advanced than ever, but there’s a catch: if the data visualization is confusing, it can actually hurt decision-making.

Poor visuals increase cognitive load, slow down analysis, and can lead to bad calls like over-policing areas that don’t actually have a sustained problem. The impact doesn’t stop with the data; it shapes how officers are deployed and how communities experience policing.

So, what kind of visualizations actually help police leaders make better decisions?

A new study with 1,195 police executives put that question to the test.

The Study

Researchers Renee Mitchell, Hunter Boehme, and Cannon Fulmer randomly assigned 1,195 law enforcement leaders (lieutenants and above) across the U.S. different types of data visualizations and asked them to make operational decisions. The goal was to see which visuals led to more accurate interpretations of crime trends and smarter resource allocation.

The four experiments compared:

• Kernel density maps vs. hot spot street segment maps
• Percent change charts vs. Process Behavioral Charts
• Variations of these with “research nudges” explaining key data concepts

In short, they wanted to know which visuals help police leaders see meaningful patterns in the data (not just short-term fluctuations) and focus on the right locations.

Experimental evidence shows police leaders may make strategic decisions depending on visuals presented: results from a multi-armed survey experiment – Journal of Experimental Criminology

Purpose To examine whether various data structures, visualizations, and “nudges” impact police leader’s (lieutenant and above) strategic crime prevention decisions. Methods We utilized a multi-armed survey experiment in which police leaders (N = 1195) were randomly assigned various data visuals and “nudges” to investigate their impact on police leader’s decision-making intentions. Results When police leaders were presented process behavioral charts and hot spot street segment maps, they more accurately identified jurisdictional crime trends and high crime areas, respectively. However, when presented with kernel density maps compared to hot spot maps, police leaders were not influenced by data visuals and no more likely to respond to crime problems with empirically promising evidence-based practices. Conclusions This study highlights the value of data presentation and visualizations in how data is presented (e.g., charts, maps) influences police leaders’ decision-making. Data analysts should present refined (micro-unit) data visuals to avoid misappropriating police resources in areas where police resources may not be heavily needed. Further, process behavioral charts provide realistic variations in jurisdictional crime trends, which were clearly interpreted by police leaders. Police researchers should consistently keep police leaders apprised of “what works, what doesn’t, what’s promising,” while police leaders should engage with data/research and consider implementing evidence-based practices.

What They Found

1. Hot Spot Street Segment Maps Beat Kernel Density Maps

When police leaders were shown micro-level street segment maps instead of traditional kernel density heat maps, they were far more accurate in identifying the highest-crime streets.

A hot spot street segment map pinpoints individual blocks or short street segments where crime is concentrated. Unlike kernel density maps, which use color gradients that blur crime patterns across neighborhoods, street segment maps show exactly where incidents occur. That precision matters, because research consistently finds that just 2% to 7% of street segments account for the majority of violent crime in a city.

Those who saw kernel density maps tended to spread resources too widely, while those viewing street segment maps concentrated on the right places which is a key advantage for precision policing.

In practice:

Hot spot street segment maps help narrow the focus, allowing agencies to deploy resources to the few streets driving most of the city’s crime. That means fewer wasted patrols, fewer unnecessary stops, and a more efficient approach to reducing violence.

2. Process Behavioral Charts (PBCs) Beat Percent Change Charts

Percent change charts, a CompStat favorite, often mislead decision-makers. They compare one period to another, like this month versus last month, making small, normal fluctuations look like major changes. A 20% jump might look alarming, but it could just be random variation, not a real shift in crime patterns.

That’s where Process Behavior Charts (PBCs) come in. Unlike percent change charts, PBCs track crime trends over time and show whether a change is statistically significant. So, in other words, whether it’s likely a real shift in crime or just random variation. In this study, PBCs were used alongside percent change charts to provide both the context of normal crime trends and the raw numbers behind them.

In the simplest terms, statistical significance tells you when something is truly different, not just part of everyday ups and downs.

In the study, police leaders who saw PBCs, with or without a short explanation of how to read them, were less likely to overreact to temporary spikes or drops. They were more likely to recognize when crime was genuinely stable.

In practice:

PBCs help agencies stay grounded in reality. Instead of constantly changing tactics based on misleading percent changes, leaders can focus their efforts when data shows a real shift in crime, saving time and resources while keeping strategies consistent.

Why It Matters

This isn’t just about pretty charts. Poor data visualization can lead to real-world consequences.

Misinterpreting a spike on a percent change chart might push a captain to increase patrols in an area that does not need them, potentially straining community trust and wasting limited resources. Likewise, when the data is unclear or the chosen solution does not work as intended, it can make police leaders hesitant to pursue a strategy that might actually be effective. On the other hand, clear, micro-level visuals like PBCs and hot spot segment maps allow leaders to focus on actual problems and make decisions with confidence.

Having spent hours walking command staff through fluctuating crime trends as a crime analyst, I have seen firsthand how misleading visuals can throw off a conversation. A percent change chart might make one month of robberies look alarming, even when the numbers are actually within the normal range. This is especially true for crimes that happen infrequently. Switching to a PBC makes the story much clearer and helps everyone see what is actually significant.

That shift, from reacting to noise to responding to evidence, is what data-informed policing is all about.

Below are a couple of resources on how to do Hot Spot Street Segment Maps and Process Behavioral Charts.

Process Behaviour Charts – An Introduction

Synopsis: This paper aims to give beginners in continual improvement an idea of what process behaviour charts are and how easy it is to put them together. For a complete understanding of process behaviour charts, including what type of data can be used, how it should be collected and interpreted, we recommend reading one of Don Wheeler’s books listed in the Bibliography at the end of the paper.

Study Limitations

Like all research, this study has its caveats. The sample was skewed toward chiefs and sheriffs, particularly from smaller agencies, so the results may not fully generalize to larger departments. Participants were given instructions to make decisions under the assumption that they had full staffing, full autonomy, and full support. While these instructions helped standardize responses, they also make it difficult to separate the influence of real-world factors, like politics, resource constraints, or agency-specific challenges, on decision-making.

The study also found that the research nudges, such as brief reminders about key evidence-based principles, did not have a strong or consistent effect on leaders’ decisions.

Still, the patterns are clear: visualization type matters, and it can shape decisions in meaningful ways.

Final Thoughts

In policing, decision-making starts with seeing the right picture. If the data is off or the visuals are misleading, everything that follows can go sideways.

So next time you’re prepping for CompStat or building a report, skip the kernel density and percent change charts. Instead, try:

• Hot spot street segment maps for precision resource allocation
• Process Behavioral Charts for understanding true trends

They might not look as flashy, but they’ll help your leadership team make smarter, calmer, and more evidence-based decisions. Using the right visuals also ties into bigger challenges in hot spot policing, like ensuring officers focus on the right locations and can be more proactive rather than reactive. For more on these strategies and how to get the most out of micro-level crime data, check out my previous posts on the challenges of hot spot policing and making officers more proactive.

Because sometimes, the charts we’ve trusted for decades aren’t the ones telling us the truth.

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Carlee Ruiz

Carlee Ruiz is the founder of PoliceResearchHub, a platform that turns academic research into practical insights for law enforcement. She brings seven years of experience as a crime analyst and justice researcher, with a focus on evidence based policing, gun violence prevention, and public safety strategy. Carlee currently works as a researcher at National Policing Institute, where she supports evaluations of law enforcement programs and criminal justice initiatives across the country. Through PoliceResearchHub, she aims to make research easier to understand and more useful for the people doing the work on the ground.