*Wichita economic development officials use a convoluted method of estimating the population of downtown Wichita, producing a number much higher than Census Bureau estimates.*

How many people live in downtown Wichita? The answer, according to Downtown Wichita, is 2,749.

This value comes from the 2019 State of Downtown Report, published by Downtown Wichita. ^{1} It is for zip code 67202, which is commonly recognized as greater downtown Wichita. While this report highlights the number of people living in downtown Wichita, it no longer reports the number of people working in downtown. ^{2}

How does Downtown Wichita arrive at the number of residents in downtown? An endnote from the report gives the details:

The 2010 U.S. Census states the population in the 67202 area code [sic] is 1,393. Per Downtown Wichita records, 1,228 units rental units have opened in the Downtown SSMID district since 2010 when the Census was taken. Per data provided directly from the Downtown residential rental properties, the absorption rates of the market rate units has an average of 85%. Per the U.S. Census Bureau, 2013-2017 American Community Survey 5-Year Estimates, the average size of renter-occupied units is 1.3 persons. Therefore, an estimate for the current population is 2,749.

^{3}

What Downtown Wichita has done is to take a reliable figure (the 2010 decennial census) and extrapolate forward to 2018. (Presumably 2018, as the report doesn’t say.)

There is a problem with this approach. The DW calculation makes use of two estimates, absorption rate ^{4} and size of renter-occupied units. Each of these is an estimate that has its own error probabilities, and those errors compound when multiplied.

There is no need to go through this roundabout calculation, as the Census Bureau has provided an estimate for the population of downtown in 2017. Data from the American Community Survey ^{5} estimates that the population in downtown Wichita for 2017 was 1,587, with a 90 percent confidence interval of plus or minus 221. ^{6} This means the Census Bureau is confident the population of downtown Wichita in 2017 was in the range of 1,366 to 1,808, that confidence factor being 90 percent. (2018 values should be available soon.)

But Downtown Wichita says the population of downtown is 2,319, which is far — *really far* — outside the range the Census Bureau gives for the 2017 population. While Downtown Wichita’s population estimate is probably for 2018, it still lies far outside the range of probability, based on Census Bureau estimates.

A nearby chart plots the Census Bureau’s population estimates (labeled ACS, for American Community Survey) with the lower and upper bounds of 90 percent confidence levels. This is compared with Downtown Wichita’s population estimate. From 2015 to 2017, Downtown Wichita’s population estimates are far above the Census Bureau’s estimates. The probability that Downtown Wichita’s figures are correct is vanishingly small.

It’s curious that Downtown Wichita, if it wants to know how many people live in downtown, doesn’t simply use the Census Bureau estimate of population. That estimate is available annually in the Bureau’s American Community Survey. Downtown Wichita didn’t use that number, but it *relied on the same body of data* to get “average size of renter-occupied units.”

Why would Downtown Wichita use the Census Bureau for one datum but not another, especially when *the Census Bureau data reports the statistic Downtown Wichita is trying to estimate in a roundabout manner?*

It’s simple. DW’s calculations produce 2,319 people living in downtown. The Census Bureau estimate is a much smaller number: 1,587.

By the way, DW’s calculations start with the 2010 Census Bureau population for downtown. Of the downtown population of 1,393 that year, 253 were men living in institutions like the Kansas Department of Corrections Wichita Work Release facility at Emporia and Waterman Streets. It has a capacity of 250. ^{7}

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Notes

- Downtown Wichita.
*2019 State of Downtown Report.*Available at https://downtownwichita.org/development/state-of-downtown. ↩ - Weeks, Bob.
*Downtown Wichita report omits formerly prominent data.*Available at https://wichitaliberty.org/wichita-government/downtown-wichita-report-omits-formerly-prominent-data/. ↩ - 2019 State of Downtown Report, page 51. ↩
- “Absorption is the amount of space or units leased within a market or submarket over a given period of time (usually one year). Absorption considers both construction of new space and demolition or removal from the market of existing space.” Institute of Real Estate Management.
*Calculating Absorption.*Available at https://www.irem.org/education/learning-toolbox/calculating-absorption. ↩ - U.S. Census Bureau, 2013-2017 American Community Survey 5-Year Estimates ↩
- U.S. Census Bureau.
*American Community Survey Multiyear Accuracy of the Data (5-year 2013-2017).*Available at https://www2.census.gov/programs-surveys/acs/tech_docs/accuracy/MultiyearACSAccuracyofData2017.pdf. ↩ - See https://www.doc.ks.gov/facilities/wwrf. ↩

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