Statement: “There’s a 130 percent increase in the number of gang homicides in the city of San Diego just in the first six months of this year,” San Diego Police Chief Bill Lansdowne said during an interview with KPBS July 31.
Determination: Mostly True
Violent crime is a category that law enforcement authorities use to track the total number of murders, rapes, robberies and aggravated assaults. Last year, San Diego police reported about 5,100 of these crimes alone.
But during in a recent interview with KPBS, Lansdowne drilled deeper into the violent crime statistics and specifically described a rise in gang-related murders.
“There’s a 130 percent increase in the number of gang homicides in the city of San Diego just in the first six months of this year,” Lansdowne said. “And those are disturbing numbers for us to deal with.”
We decided to Fact Check whether the Police Department’s own numbers support the 130 percent jump. Lansdowne cited the spike to support the need for additional funding and it certainly sounded like a troubling trend.
Just to be clear, the purpose of this Fact Check is not to determine whether the murders were actually gang-related or whether the deaths were even murders. Our narrow focus is figuring out whether Lansdowne accurately described the number of deaths that his officers believed were gang-related murders at the time of the KPBS interview. It’s possible the number could change depending on the results of ongoing investigations.
To help understand Lansdowne’s claim and additional context, I’ve illustrated the number of gang-related murders and all murders since 2007 in the graphic below. This information comes from the Police Department’s homicide unit and crime reports posted online by Sandag.
Lansdowne’s specific comparison was accurate. Police reported 14 gang-related murders during the first half of this year and six during the same period last year. The difference between those numbers is 133 percent — close to the figure Lansdowne cited.
The graphic also shows why the spike in murders this year is unusual. Police reported more between January and June than the same period in each of the past five years. The six-month total this year exceeds the annual total in each of the past three years, too.
I asked police last week why gang-related crime appears to be climbing, but police said an authority on the subject wasn’t immediately available to comment. If I hear back, I’ll update this post or write a new story about the Police Department’s response.
In the meantime, we’ve rated Lansdowne’s statement Mostly True. His statistic was accurate, but there is a key nuance to consider about how it was calculated. The percentage represented the difference between two relatively low numbers.
The scale of the numbers is important because using percentages to measure the difference between two low numbers can lead to a skewed impression. Let’s say police reported three traffic accidents on a street this month and just one the month before. That’s technically a 200 percent increase.
Earlier this year, Lansdowne himself cautioned against using percentages to measure the difference between two low numbers. Discussing crime trends with a City Council committee, Lansdowne said:
Percentages sometimes don’t tell the full story … Our numbers are so low for crime in the city of San Diego that just a few numbers either way — five or six crimes in a city of 1.4 million or in a community that has 180,000 people — are important to us, but it’s not a crime wave that’s taking place. Those are the normal fluctuations that take place in a city.
In the case of gang-related murders, the number of crimes didn’t change by five or six. It increased by eight.
Like VOSD on Facebook.