state, while the ACS provides estimates on the basis of a uniform methodology across the country.

Despite their differences, the ACS estimates and state counts represent conceptually similar entities—both measure the number of school-age children in the state that have not mastered English. Thus, some level of correspondence between the two measures would be expected.

We conducted a series of analyses to evaluate the consistency of the ACS and state-provided percentages of ELL students. In order to facilitate comparisons between the ACS estimates and state-provided counts we limit the ACS population to those aged 5-18 and only to those enrolled in public school. It is important to point out that by limiting the ACS estimate to this comparison group, we have created an ACS-based variable that is more limited than the legal definition of ELL students used by the U.S. Department of Education (DoEd).

As detailed in Chapters 2 and 4, there are two ways to calculate the percentages: the number of ELL children in the state as a percentage of the total number of ELL children in the country, which is the state’s share of ELL children; and the proportion that ELL students constitute of the total number of enrolled students, which is the rate of ELL students. We also conducted a series of multiple regression analyses to evaluate the correspondence between the ACS and state estimates. In these analyses, we focus on rates, rather than shares, in order to assess the degree of consistency of the two data sources in a manner that is relatively independent of state population. That is, analyses that focus on state counts or shares are dominated by the agreement between the ACS and state-provided numbers for some states, suggesting only that certain states (notably, California and Texas) are large and others are small, a trivial finding that provides little information about how well the two measures agree on estimation of ELL students.

COMPARISON OF SHARES OF ELL STUDENTS

In this section we compare the state shares (of Title III funding) based on ACS estimates with those based on state-provided counts. Since the funding allocations are based on each state’s share of ELL students in the country, this analysis allows us to evaluate how the allocations would be affected on the basis of which measure was used, as well as the ways that the measures would result in different funding decisions. We compare the shares in three ways: (1) the percentage shares themselves, (2) the ratio of the shares, and (3) the absolute differences in the shares across the states.

State Percentage Shares

Table 5-2 shows each state’s share of ELL students based on the two data sources. The first four columns on the left-hand side of the table show the shares based on the ACS estimates. Included are 1-year estimates for 2006, 2007, and 2008



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