DALLAS (CBSNewYork) — Despite efforts by police and city leaders to fight crime, fluctuations in murder rates may follow a 55-year cycle against which local problems have little long-term impact.

According to the study, factors like segregation and concentrated pockets of poverty play a bigger role than factors such as opioids or civil unrest.

For example, some attributed the rise in homicide rates in Chicago and Baltimore to decreases in police stops and arrests that resulted from civil rights litigation. The study’s authors point out that New York City, which also has experienced decreases in stops and arrests, has not seen increased homicide rates.

Mayor Bill de Blasio and Police Commissioner James O’Neill touted a historic drop in NYC crime with 286 murders in 2017, down from a peak of more than 2,200 in 1990.

“If you look at the trends over time, you can often see ups and downs of that magnitude,” said Dr. Andrew Wheeler, assistant professor of criminology in the School of Economic, Political and Policy Sciences.

Researchers Wheeler and Dr. Tomislav V. Kovandzic at the University of Texas at Dallas identified the trend after looking at a U.S. Department of Justice report and did an analysis of broader trends rather than the year-over-year numbers normally used by politicians and journalists.

“That doesn’t mean we shouldn’t pay attention to short-term spikes, as they may – if not addressed – contribute to a city’s long-term homicide level,” Kovandzic said. “But it does mean policymakers and journalists could be missing the forest for the trees if they insist on focusing on the here and now.”

“We hope that this information can illustrate that homicide rates are volatile, so it’s important to consider the size of a city and historic levels of homicide when analyzing homicide rates,” Wheeler said. “Researchers focusing only on very recent homicide trends are likely to overestimate the effect of recent events.”