Editor's note: The maps below automatically update daily, when the state's data is updated.
New: COVID-19 is on the rise in Arizona. Two new maps help you understand the outbreak.
The first ZIP code map shows the average rate of new infections over the most recent seven-day period. This data helps you see where a new rise in infections may be happening.
The second map shows you data from the entirety of the pandemic. This map doesn't reflect active infections, as many of these cases may be from early 2020. It gives you an approximation of how many people in an area have tested positive, in total.
Note, data may be missing from some ZIP codes, and the state suppresses data from some areas that are under tribal control. Read beyond the maps for more details on how these numbers are calculated.
This map shows recent cases:
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How this map differs from Arizona Department of Health Services coronavirus data
State health officials publish data daily about the number by ZIP code, but the state's data dashboard shows only the cumulative numbers since the beginning of the coronavirus pandemic. That makes it difficult to distinguish areas of old outbreaks from areas of new ones.
How the data on this map is calculated
New numbers daily: Each day as new data is published, the map updates. (Because of delays in test results, state health officials say, the data released on any given day represents the number of cases four to seven days earlier.)
A 7-day average: The hotspots map takes the number of new infections reported each day for the past seven days, and displays the average. (Results fluctuate over weekdays and weekends, so the average prevents a one-day blip from skewing the results.)
Rate per 10,000 people: For each ZIP code, we take that seven-day average of new cases, and calculate the rate per 10,000 people. This helps you compare ZIP codes, since each area has a different population. (For example, five new cases in a ZIP code with 50,000 people might be a relatively small number, whereas five new cases in a ZIP code with 1,000 people might be a significant spike.) The rate-per-10,000 is the basis for the color code on the map.
Compared with two weeks earlier: When you click or tap on any ZIP code, you'll see a line that says "higher than two weeks ago" or "lower than two weeks ago." For this calculation, we take the seven-day average rate of cases per 10,000 people and compare it with that same rate two weeks prior. For example, if the average rate today is 10 cases per 10,000, and two weeks ago it was 5 cases, the map would show today's rate is "100% higher than two weeks ago."
Total number of cases
This map shows cases since the beginning of the pandemic and the share of the population with a reported case in each ZIP code:
What to know about ZIP codes on these maps
Population figures: For this map we use 5-year population estimates for each ZIP code area from the US Census Bureau's 2018 American Community Survey.
A few ZIP codes do not have any population data recorded in this data set, and therefore will not show a "Rate per 10k" or "Share of population" figure — even though they have had positive cases. These include 85329 and 85378 in the West Valley, and 86005 near Flagstaff.
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Home addresses: The state has said its data is mostly drawn from records showing a patient's home address. However, if a patient's residence is unknown, the case is mapped to the address of the provider or the reporting facility, so it's possible some cases shown on this map do not correspond to a patient's home in that area.
But the state's map indicates that, generally, more than 90 percent of the cases were mapped to the address of the patient's residence.
Tribal areas: State records suppress testing data from some ZIP codes where more than 50% of the population is tribal residents. ADHS's website says those areas are "pending tribal approval."
Data on coronavirus cases relative to population comes from AZ Data Central. Support journalism that helps you make better decisions about how you live. Please subscribe.
This article originally appeared on Arizona Republic: Coronavirus by Arizona ZIP code: Map with COVID-19 data