placestats

Black Protestant adherents and Average test score

A county is not a congregation. Counties where more people are counted as adherents (members of a religious group) also tend to differ on the other measure, and that is all. It does not follow that the adherents are the people with the different score. Making that leap is called the ecological fallacy: reading a pattern across places as a fact about individual people. It is as easy to fall into here as with the voting pairs. Two things about the counting matter too. Adherents are counted where their congregation meets, not where they live, so thirty very small counties exceed 100%. And a denomination that did not report is missing, not zero. That undercounts membership most where churches are least formally organised.

Where Black Protestant adherents is higher, Average test score tends to be lower. The link is weak: -0.35 across 2,756 counties, on a scale from −1 (opposite) to +1 (in step). That figure compares places with the same population density, income and education, so those differences can't explain it. It holds inside states too. Measured separately within each of 38 states, the middle value of the link is -0.24.

Holds after adjusting

Every place, plotted

One dot for each place reporting both measures. Hover over or tap a dot to see its name and values. The thin line is the straight line that best fits the dots. The bold line, shown for counties, is the link after adjusting for density, income and education. A dot far from the lines is a place that does not follow the pattern.

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What each measure is

Black Protestant adherents

Members of the historically Black Protestant churches, as a share of the population. Their central records are thinner than most, so this is the least complete of the six groups. Which of these churches reported also differs between the 2010 and 2020 studies, so part of any change between them is who reported, not real membership.

· Religion Census BPRTRATE (2010, 2020)

Average test score

How far above or below the national average children here score on tests, in grade levels. Minus one means about a year behind. It reflects everything in children's lives, not only their schools.

Stanford Education Data Archive · SEDA cs_mn_avg_ol

Highest and lowest

Where each measure is highest and lowest among the places reporting both (2023), with the other measure beside it. This is shown for every size of place where both are published. Metro-area values are added up from their counties. A measure that cannot be added up across counties, such as a middle value (median), has no metro figure. Counts are shown per 1,000 residents, since raw totals would only list the largest places. Cities and towns and ZIP codes are shown where the Census survey or the CDC publishes them; most other sources stop at the county. They are shown for places of 5,000 residents or more, and only where the survey’s margin of error is small enough for the figure to be usable. The CDC publishes its health estimates for cities in a version adjusted for age, so places with older or younger people can be compared fairly, but not for ZIP codes.

Counties

By black Protestant adherents

Black Protestant adherentsAverage test score
Highest
Nevada County, AR34.6-0.209
Adams County, MS34-0.677
Northampton County, NC29.6-0.255
Macon County, AL29.2-0.838
Lowndes County, MS28.8-0.232
Lowest
Teller County, CO00.217
Summit County, CO00.347
San Miguel County, CO00.364
Saguache County, CO0-0.322
Routt County, CO00.539

By average test score

States — Average test score is not published for states

By black Protestant adherents

Black Protestant adherentsAverage test score
Highest
District of Columbia10.4—
Mississippi8.7—
Alabama7.65—
Arkansas6.31—
Tennessee5.74—
Lowest
Vermont0—
New Hampshire0.02—
North Dakota0.05—
Montana0.06—
Idaho0.07—
Metro areas

By black Protestant adherents

Black Protestant adherentsAverage test score
Highest
Columbus, MS26-0.303
Magnolia, AR25.7-0.202
Camden, AR25.5-0.466
El Dorado, AR22.5-0.265
Greenville, MS22.1-0.59
Lowest
Zapata, TX0-0.398
Yankton, SD00.118
Worthington, MN0-0.178
Wooster, OH00.329
Woodward, OK0-0.147

By average test score

Black Protestant adherentsAverage test score
Highest
Vineyard Haven, MA00.583
North Platte, NE00.553
Los Alamos, NM00.543
Sheridan, WY00.536
Lewisburg, PA1.90.521
Lowest
Forrest City, AR12.9-0.774
Shawano, WI0-0.756
Selma, AL12.3-0.724
Clarksdale, MS18.2-0.69
Eufaula, AL-GA14.5-0.647

Counties furthest from the pattern

Compared with the straight line that best fits all 2,772 counties: the five with far more average test score than their black Protestant adherents would suggest, and the five with far less.

Black Protestant adherentsAverage test score
Above the line
Nevada County, AR34.6-0.209
Camden County, NC16.40.265
Skagway Municipality, AK00.738
Forsyth County, GA0.030.713
Williamson County, TN1.20.621
Below the line
Kusilvak Census Area, AK0-1.31
Bethel Census Area, AK0.8-1.27
Todd County, SD0-1.21
Sioux County, ND0-1.15
Oglala Lakota County, SD0-1.12

Two series, one county

Both measures over time for a county you pick. The two charts are stacked, so they share only the years along the bottom. You can pick from the thirty largest counties reporting both. This panel covers 2010–2024, and a measure published only once shows as a single dot.

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Every version of the link

Each row measures the same link, from −1 to +1, in a different way. If the rows mostly agree, the link does not depend on one choice of method.

Before adjusting for anything-0.4352,756 counties reporting both
After adjusting for density, income and education-0.349the part of the link that is not just how urban, rich and educated a place is
Also adjusting for population size-0.363size taken out as well as density
Also comparing only within each state-0.294each county is compared only with others in its own state, so this is no longer a comparison between states
Giving bigger counties more weight-0.365the adjusted link for the average resident rather than the average county. With this weighting, the data counts for about 267 equally weighted counties
Middle value inside single states-0.238the link worked out inside each of 38 states with at least 20 counties reporting
Using ranks, after adjusting-0.296uses each county’s rank, not its value, so a few extreme counties cannot create the link

How much to believe it

Could it be chance?

The p-value is the chance of seeing a link this strong if there were really none. A value of 0.05 or less means the link is unlikely to be chance. Very small values are written in short form: 3.1e-16 means 0.00000000000000031, and the bigger the number after “e-”, the smaller the value. Treating every county as a separate case gives p = 7.6e-80. But counties in the same state tend to resemble each other, so the better figure allows for that: p = 2.9e-8. The site tested 20,910 pairs, and testing so many turns up some flukes. The q-value allows for that too. For this pair it is 5.4e-79.

Do nearby places look alike?

Moran’s I measures how much nearby places look alike: 0 means no map pattern, and higher means neighbours are more similar. For the part of each county that the adjustment leaves unexplained, it is +0.41 (p = 0.001). That unexplained part still clusters on the map. So some regional factor shared by both measures is not accounted for.

Did they change together?

Not measurable: at least one of these is published for too few of the years a change needs (2014–2019 or 2019–2023), or for too few counties in both.

Related pairs

Association only. Nothing here shows that either measure changes the other. This describes counties, not the people in them. Two measures going together across places does not mean the same people have both. How the US county data works · Explore Black Protestant adherents and Average test score