Cellphone data suggests Bay Area not as compliant with new shutdown as it was in the spring

Some have questioned whether the new stay-at-home order currently in effect in the Bay Area would be followed as closely as the one in effect in the spring, and new cellphone data would support the theory compliance is not as high now as it was at the start of the pandemic in March.

The data company Unacast, a firm that collects cellphone location data from millions of phones for private companies, created the “Social Distancing Scoreboard” that shows which counties in California and beyond are seeing compliance in getting people to stay home. Each county and state is graded on an A through F scale based on three criteria: change in average mobility based on distance traveled, change in nonessential visits and difference in encounter density.

In the spring, the firm used only change in average mobility when compared to normal times to calculate grades, but has since added the other two criteria.

“Travel distance is one aspect, but of course people can travel far without meeting a soul or travel 50 feet and end up in a crowd — so we know that the real world picture can be quite complex,” Unacast writes in its methodology. “As noted above, changing behavior will trigger adjustments in our data strategy. That’s why, post launch, we will be continuously working to improve our social distancing models.”

On March 30 — two weeks after six Bay Area counties issued a stay-at-home order and one week after it was adopted statewide — every Bay Area county except one received an “A” grade thanks to dramatic decreases in average mobility.

However, data pulled from Dec. 17 — almost two weeks after five Bay Area counties adopted the state’s stay-at-home order early — shows that only one county is receiving an “A” grade.

It is important to note that the comparison is not completely direct. The current stay-at-home order allows for outdoor activities that were banned in the spring, such as going to a park or golf course. On Unacast’s end, in addition to two new criteria, the firm has also changed its letter grade thresholds. As you can see below, most Bay Area counties are posting near-identical change in average mobility numbers as they did in the spring, but those numbers now qualify for the “B” range as opposed to the “A” range.

The change suggests most Bay Area counties should have gotten “B’s” in the spring as opposed to “A’s,” but the general takeaway still stands: The region is generally seeing less compliance now than it did at the end of March. Here’s a rundown of the nine Bay Area counties’ “social distancing scores” according to Unacast:

San Francisco County (issued early stay-at-home order in both March and December)

March 30 grade: A (65% decrease in average mobility)

Dec. 17 grade: 

Dec. 17 grade breakdown:

Change in average mobility: B (50-70% decrease)

Change in number of nonessential visits: F (less than 55% decrease)

Change in encounters density: F (less than 40%)

San Mateo County (issued early stay-at-home order in March but not December)

March 30 grade: A (63% decrease in average mobility)

Dec. 17 grade: C

Dec. 17 grade breakdown:

Change in average mobility: B (50-70% decrease)

Change in number of nonessential visits: C (60-65% decrease)

Change in encounters density: D (40-74% decrease)

Alameda County (issued early stay-at-home order in both March and December)

March 30 grade: A (51% decrease in average mobility)

Dec. 17 grade: C+

Dec. 17 grade breakdown:

Change in average mobility: B (55-70% decrease)

Change in number of nonessential visits: B (65-70% decrease)

Change in encounters density: D (40-74% decrease)

Santa Clara County (issued early stay-at-home order in both March and December)

March 30 grade: A (61% decrease in average mobility)

Dec. 17 grade: B-

Dec. 17 grade breakdown:

Change in average mobility: B (55-70% decrease)

Change in number of nonessential visits: A (greater than 70% decrease)

Change in encounters density: D (40-74% decrease)

Contra Costa County (issued early stay-at-home order in both March and December)

March 30 grade: A (48% decrease in average mobility)

Dec. 17 grade: C+

Dec. 17 grade breakdown:

Change in average mobility: B (55-70% decrease)

Change in number of nonessential visits: B (65-70% decrease)

Change in encounters density: D (40-74% decrease)

Marin County (issued early stay-at-home order in both March and December)

March 30 grade: A (56% decrease in average mobility)

Dec. 17 grade: A-

Dec. 17 grade breakdown:

Change in average mobility: B (55-70% decrease)

Change in number of nonessential visits: A (greater than 70% decrease)

Change in encounters density: A (greater than 94% decrease)

Napa County (issued stay-at-home order when the state required it in March and December)

March 30 grade: A (54% decrease in average mobility)

Dec. 17 grade: B

Dec. 17 grade breakdown:

Change in average mobility: B (55-70% decrease)

Change in number of nonessential visits: C (60-65% decrease)

Change in encounters density: A (greater than 94% decrease)

Solano County (issued stay-at-home order when the state required it in March and December)

March 30 grade: B (37% decrease in average mobility)

Dec. 17 grade: C+

Dec. 17 grade breakdown:

Change in average mobility: B (55-70% decrease)

Change in number of nonessential visits: D (55-60% decrease)

Change in encounters density: B (82-94% decrease)

Sonoma County (issued early stay-at-home order in December but not March)

March 30 grade: A (41% decrease in average mobility)

Dec. 17 grade: B+

Dec. 17 grade breakdown:

Change in average mobility: B (55-70% decrease)

Change in number of nonessential visits: B (65-70% decrease)

Change in encounters density: A (greater than 94% decrease)

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