It didn’t take Donald Trump long to respond to the horrific terror attack in Manhattan on Tuesday in which eight people were killed and 12 wounded. Within 24 hours, the president tweeted: “We must not allow Isis to return, or enter, our country after defeating them in the Middle East and elsewhere. Enough!”

In fact, terrorist groups are far from defeated in the Middle East or elsewhere in the world. As the graphic above shows, Tuesday’s attack was surprising because it took place in a region that is very safe relative to other parts of the world.

Data

The numbers for this image come from the Global Terrorism Database. It’s an enormous dataset that tracks terrorist attacks going back to 1970, keeping information on things like weapons used, motives, targets and of course the date and location of the incident.

The information is managed by Start, a US Department of Homeland Security Center of Excellence located at the University of Maryland. But it’s far from perfect. For one thing, its methodology has changed, which means that comparisons over time might paint a misleading picture about how much terrorist attacks have increased in frequency. These flaws are particularly disappointing given that this is the best public data that exists on terrorism.

Design

I was inspired by this graphic by Johan Ekman this week. But I wanted to check his information, update it and add extra detail. My first step was to download the most recent version of the Global Terrorism Database, which includes 383,554 fatalities from terrorism.

The 170,350 terrorist attacks in this list span the period from 1 January 1970 to 31 December 2016. There were, however, many incidents where a specific date was not known, only a year – these were listed in the database with dates such as 0/0/1970. Where specific dates weren’t available, I excluded the incidents from the dataset. This meant that 1,211 fatalities (or 0.3% of all the fatalities in the database) were not included in my final analysis.

I first created a simple timeline of all fatalities. I immediately noticed that the original graphic by Ekman excluded an important event. For some reason, it didn’t include one of the deadliest attacks of the past 47 years. The database provides the following description:

06/12/2014: Assailants abducted approximately 1,686 soldiers from Camp Speicher in Tikrit city, Saladin governorate, Iraq. Two captives escaped custody and at least 1,500, if not all of the remaining victims, are presumed dead. The Islamic State of Iraq and the Levant [Isis] claimed responsibility and stated that the attacks were in revenge for the killing of [Isis] leader Abdul-Rahman al-Beilawy.

In 2015, according to a Reuters report, Iraqi forensic teams began exhuming bodies from their mass graves. That single terrorist attack (which I hadn’t heard of before looking at this database) radically changes the scale of the chart.

Next, I charted fatalities in North America and western Europe. The high bar there is 11 September 2001 when, according to the database, 2,998 people were killed. (As with many terrorist attacks, estimates of the final number of fatalities can vary between sources.)



Fatalities from terrorist attacks in the west. Photograph: Mona Chalabi

Then I charted fatalities in other regions:

Fatalities from terrorism around the world. Photograph: Mona Chalabi

I immediately noticed a gap in 1993 – and the explanation is a surprising one. It turns out that the data was originally written on index cards and the researchers lost the cards for 1993 before they were able to turn them into electronic copies. Other than that, there’s not much to be observed from this chart, since it’s so difficult to discern which regions have more fatalities on any given day.



To exaggerate those differences, I changed this chart so I could compare the percentage of fatalities on each day that come from each region. Now, it’s clear that most fatalities occur in sub-Saharan Africa, south Asia and the Middle East and North Africa.

The regions where fatalities from terrorism are most likely to occur. Photograph: Mona Chalabi

Finally, I limited the data to the most recent 10 years so as not to include older, less accurate, data from the source. I drew the outline of the chart by hand then pasted on the specific bars (which are too narrow to draw by hand) from the charts I created in Microsoft Excel. It’s not perfect, but neither is the data behind it.

What’s unambiguous in the data and in the final design is that deaths from terrorism remain rare in North America and western Europe, compared with the rest of the world.