Is California staying home? Here’s what GPS phone data say in coronavirus pandemic

How well are California residents staying home during the coronavirus pandemic?

A data company is using GPS data from millions of mobile devices to analyze human movement in the U.S. since the beginning of February.

SafeGraph, which has companies such as Verizon and Sysco for clients, compiles GPS data to track how people in the U.S. are responding to the pandemic. It’s offering the information to researchers, nonprofit organizations and government officials.

California was the first to issue a statewide stay-at-home order in the U.S. when Gov. Gavin Newsom announced the restrictions on March 19.

The state also ranks near the top of the country in the data analysis’ stay-at-home index.

California stay-at-home data

• Shelter-in-place index: 22.06%

This figure represents the percentage of people staying home above a baseline on Saturday, the most recent day available. The baseline was recorded in the first week of February.

It means about 22% more California residents are staying at home all day compared to early February.

The state ranked sixth in the U.S. by this metric.

Overall, about 46% percent of California residents stayed home, the data show.

U.S. social distancing data

• Stay-at-home index: 18.52%

Across the country, more people are staying home each day, according to the data.

Nearly 19% of American stayed at home on Saturday, a sign more Americans are listening to social distancing guidelines.

That’s a jump from approximately negative 3% on March 9, meaning about 3% more people were out of the house compared to the baseline week in early February.

On that day, the U.S. had 560 confirmed cases and neither the World Health Organization or the CDC had officially declared a pandemic, according to CNN. Now the country has more than 450,000 confirmed cases and more than 16,000 deaths, according to Johns Hopkins University.

New Jersey and New York lead the country in the analysis’ shelter-in-place index at 29.52% and 24.86%, respectively.

Stay-at-home methodology

SafeGraph is providing the stay-at-home information dashboard because it’s a primary way governments are combating the coronavirus pandemic. The company says its index is different than other social distancing data sets because it’s not based on total distance traveled.

“Whether to visit a neighbor or to visit the grocery store, whether the distance traveled is 10 miles or 0.1 miles, all ‘away-from-home’ events are classified the same in this dashboard,” according to the company. “We think this is a useful metric because one does not need to travel long distances to undermine social-distancing and enable viral transmission.”

The data is generated by GPS pings from 45 million anonymous smartphones, according to the company. An “event” is classified as each time the device leaves its home. A “home” is defined as the nighttime location over a six-week period.

The company says it doesn’t know or want to know the the precise home address of the devices.

This story was originally published April 9, 2020 at 5:35 PM with the headline "Is California staying home? Here’s what GPS phone data say in coronavirus pandemic."