Evaluating the Local Employment Dynamics Program as a Source of Journey-to-Work Data for Transportation Planning1

Wende A. Mix, Ph.D.Associate Professor, Dept. of Geography and Planning, Buffalo State College

Philip N. Fulton, Ph.D.Economic Research Services, USDAIn 2003, the U.S. Census Bureau conducted a pilot project for the Bureau of

Transportation Statistics to determine the feasibility of producing journey-to-work data from the Census Bureau's Local Employment Dynamics (LED) Program that could be used for transportation planning. The project resulted in several data files containing place of residence, place of work, wage, and industry classification data for the states of Illinois and Florida. Using the LED data for Illinois, this paper presents the results of an initial assessment of the comparability of LED journey-to-work data with data from the decennial census and the American Community Survey. Suggestions are made for next steps in the project and ways to improve the LED products to further enhance their potential utility for transportation planning.

This paper presents an exploratory assessment of the comparability of LED journey-to-work data with data from the decennial census and the ACS. More specifically, the paper documents the results of comparisons of the 2001 LED work trip data for Illinois from the BTS project with data from the 2000 census and the 2001 ACS. The purpose of this analysis is to inform future decision making on the part of BTS and the Census Bureau regarding continued development of transportation planning data from the LED Program. With the transition from the census long-form to the ACS as the main source of journey-to-work data for use in transportation planning, the transportation planning community is actively engaged in understanding how data from the ACS can be integrated into their planning activities. In the context of this transition, now is an opportune time to also examine the utility of employment data from the LED Program as a possible component in an integrated transportation data system.

[1] The views expressed in this paper are solely the authors’ and do not necessarily represent the views of the U.S. Bureau of the Census, the Bureau of Transportation Statistics, or the Illinois Department of Employment Security.

Abstract

Purpose of the Study

Results of the StudyWorkers:In comparing estimates of total workers, the accuracy of the LED data can be affected by employees missing from the Unemployment Insurance wage records, employees whose residence address could not be obtained or geocoded, or the suppression of small blocks with few resident workers. Census and ACS data can be affected by the exclusion of second jobs, workers that were not "at work" during the reference week, and sampling error. But, all things being equal, we would expect the LED estimate of resident workers based on total jobs to be higher than the census or ACS estimates of total resident workers based on employed persons.

Table 1 shows two LED estimates of the number of workers residing in Illinois derived by summing the records from the H-B Characteristics File of resident workers in each block and the O-D File of workers in block-to-block commuter flows. Counts of self-employed workers, unpaid family workers, and Federal government workers, available in standard ACS and census tabulations of labor force data, are subtracted from the worker total in order to more closely approximate the LED universe. Also, since the ACS and census estimates are for workers by place of residence, they include both workers who lived and worked in Illinois and workers who lived in Illinois but worked outside the state. The LED estimates only include workers who lived and worked in Illinois.

Methods The basic question we seek to answer in this exploratory analysis is:

How comparable are the journey-to-work data from the LED to the census and the ACS in terms of the number of workers, the distribution of worker flows, and the magnitude of those flows?

(1) County Level Comparisons

Total workers, Resident workers, Resident workers working inside and outside county of residence, Wage and earnings data

(2) Tract Level Comparisons

Total flows by geographic area type, Internal tract flows, Distance-decay estimation by area type, directional distribution of flows analysis for individual tracts.

Only part of the completed analysis is included in this poster.

Data Source Number of Workers

90-Percent Confidence Interval

Lower Bound

Upper Bound

2001 LED Home-Block (H-B) Characteristics File

5,150,511 n/d n/d

2001 LED Origin-Destination (O-D) Matrix File

4,301,766 n/d n/d

2000 Census 5,203,076 5,194,009 5,212143

2001 ACS 5,266,743 5,194,258 5,339,228

2000 Census, adjusted to exclude workers who worked out-of-state

5,036,578 n/d n/d

2001 ACS, adjusted to exclude workers who worked out-of-state

5,087,674 n/d n/d

Note: The ACS and census estimates are for the number of employed civilian persons 16 years and older residing in Illinois, excluding self-employed workers, unpaid family workers, and federal government workers which were subtracted from the total to more closely approximate the LED coverage universe. Since the LED estimates do not include workers that lived in Illinois and worked outside the state, the ACS and census estimates excluding out-of-state commuters were calculated to provide comparability.n/d = Not determinable Sources: 2001 ACS Supplementary Survey Summary Tables P068 and P043. 2000 Census Summary File 3 Tables P51 and P26.

Table 1. Comparative Estimates of the Number of Workers Living in Illinois

County ACS

90-Percent Confidence Interval

Census

90-Percent Confidence Interval

LED

ACS, excluding workers

who work out-of-state

Census, excluding workers

who work out-of-state

Lower Bound

Upper Bound

Lower Bound

Upper Bound

Cook 2,206,950

2,169,319

2,244,581 2,175,454 2,167,087 2,183,821 2,242,317 2,182,674 2,151,524

DuPage 429,570

415,465

443,675 425,123 421,470 428,776 454,572 426,563 421,722

Kane 201,030

191,613

210,447 177,590 175,300 179,880 191,873 200,628 176,347

Lake 280,438

275,163

285,713 269,354 266,660 272,048 295,126 274,268 264,236

McHenry 126,363

119,172

133,554 121,067 119,300 122,834 132,039 124,973 119,372

Will 244,832

234,421

255,243 223,437 220,929 225,945 257,214 240,670 220,532

Madison 106,691

100,081

113,301 111,017 109,281 112,753 89,804 72,016 80,487

St. Clair 98,700 91,290

106,110 95,447 93,800 97,094 81,875 72,150 67,958

Winnebago 114,213

106,145

122,281 122,746 120,944 124,548 131,035 109,302 118,450Note: The ACS and census estimates are for the number of employed civilian persons 16 years and older residing in each county, excluding self-employed workers, unpaid family workers, and federal government workers which are subtracted from the total to more closely approximate the LED coverage universe. Since the LED estimates do not include workers that lived in Illinois and worked outside the state, the ACS and census estimates excluding out-of-state commuters were calculated to provide comparability.Sources: 2001 ACS Supplementary Summary Table P068 and P043. 2000 Census Summary File 3 Tables P51 and P23. 2001 LED H-B File.

Table 2. Comparative Estimates of the Number of Workers Living in Selected Illinois Counties

The 2001 ACS included nine Illinois counties: six counties (Cook, DuPage, Kane, Lake, McHenry, and Will) in the Chicago-Naperville-Joliet, IL-IN-WI MSA, one county (Winnebago) in the Rockford, IL MSA, and two counties (Madison and St Clair) in the St. Louis, MO-IL MSA. Table 2 shows comparative estimates of the number of workers residing in each of these counties based on the LED, the census, and the ACS. The ACS and census estimates in the table again exclude self-employed workers, unpaid family workers, and Federal government workers in order to more closely approximate the LED universe. As with the state level data, the ACS and census estimates include workers who work outside Illinois, while the LED estimates do not. Again, alternative ACS and census estimates, adjusted to exclude out-of-state commuters were calculated using the percent of county workers found to be working outside Illinois in the ACS and the census.

As expected, the LED estimates of the number of workers residing in each county are consistently higher than the ACS and census point estimates, with the exceptions of the ACS estimate for Kane County and both the census and ACS estimates for Madison and St. Clair counties. However, when the ACS and census estimates are adjusted to exclude out-of-state commuters to make them more comparable to the LED universe, the data for Madison and St. Clair fall in line with the general pattern. The anomaly with the Kane County ACS estimate stems from what appears to be an error in the ACS place-of-work data. The data show too few out-of-state commuters, so the adjustment is too small to bring the data into the proper relationship. The census data for Kane County show the more typical pattern.