Deriving State-Level Estimates from Three National Surveys: A Statistical Assessment and State Tabulations. E. Generalization of the Ability to Produce Accurate Direct Estimates at the State Level Using a Single Time Period

05/04/1998

By examining the results of the previous section and the distribution of sample sizes across the states, it is possible to make some general comments on the ability to produce accurate state estimates from a single time period's data for the CPS and SIPP. Unfortunately, the lack of data from the redesigned NHIS makes it impossible to make statements about that survey, beyond the fact that for many states the NHIS sample sizes are so small that direct estimates from a single time period would be subject to large variability. This assessment has also not taken into consideration the effect that the lack of state-stratification has on SIPP estimates. Research is currently being conducted on how that will affect state estimates. Table 5 summarizes the results found in the previous section. It is important to remember that the actual number of completes in a state is a random variable that will change with each round of data collection. Therefore, the exact numbers shown in Table 5 are only approximations for future survey rounds. This is particularly true for subpopulations. Again, the SIPP data combine information for nine states. Therefore, we assessed the 41 states and the District of Columbia for a total of 42 possible "states."

Given the relatively low precision requirements used in the previous section, it is possible to estimate the proportion of the total population in a state with a characteristic for almost all states from either survey. For the CPS, this is also true for children and, except for Alaska, the elderly. The CPS is only able to support estimates for blacks for about half of the states and 30 to 40 percent of the states for Hispanics, depending upon the measure. Given the smaller sample size of the SIPP, its ability to support such estimates for subpopulations is more limited than the CPS. For children and the elderly, the SIPP can support estimates for the majority of states. For blacks, it can produce estimates that meet these levels of precision for around 20 states and for Hispanics in less than 10 states.

If other characteristics of interest to ASPE are contained in the core CPS interview, it would be possible to increase the sample size in each state significantly by combining data from different months of the survey. (CPS respondents are interviewed in four successive months, then dropped for eight months, then interviewed again for the following four months.) Even when this is true, the respondents in a given state are generally all from just a few primary sampling units (PSUs). This results in state-level standard error estimates that are quite unstable. To accurately estimate the accuracy of the estimates, it would be necessary to use some form of generalized variance function model that smoothes precision estimates derived from the different states.

In terms of specific states, the 1996 CPS permits analyses of all of the selected characteristics for the subgroups examined at the specified precision criteria for eight states - California, Florida, Illinois, Massachusetts, New Jersey, New York, Pennsylvania, and Texas. The SIPP permits analyses for six states -- California, Florida, Illinois, New Jersey, New York, and Texas. The binding constraint for the data for a number of states is the sample size for Hispanics. If the selected characteristics for Hispanics are not included in assessing which states meet all of the criteria, 16 states are added for the CPS and three states are added for the SIPP. For the SIPP, work disability among those aged 65 to 69 also caused several states to fail to meet all of the criteria. Table 6 and the two maps (Exhibit 1 and Exhibit 2) provide summary information regarding the number of criteria met for the states. The appendices provide state level detail for each of the selected characteristics and criteria.

It is important to repeat that the precision requirements used in Table 5 and Table 6 are quite arbitrary. If narrower confidence intervals are desired, the number of states meeting the cut-off will obviously be reduced.

  TABLE 1. Percent Living in Poverty and Actual Sample Size by State, March 1996 CPS  
  Percent Living in Poverty Actual Sample Size
  Black     Hispanic     Other     Total     Black     Hispanic     Other     Total  
Alabama 41% 25% 11% 21% 507 23 1,190 1,720
Alaska 21% 8% 7% 8% 64 48 1,405 1,517
Arizona 49% 31% 12% 18% 64 747 1,325 2,136
Arkansas 38% 32% 12% 17% 254 23 1,483 1,760
California 30% 34% 11% 19% 677 5,601 6,626 12,904
Colorado 28% 25% 7% 10% 55 311 1,418 1,784
Connecticut 32% 48% 4% 11% 102 187 1,016 1,305
Delaware 16% 28% 10% 11% 208 61 982 1,251
District of Columbia   31% 21% 9% 25% 761 80 320 1,161
Florida 36% 29% 11% 18% 772 1,599 4,169 6,540
Georgia 23% 20% 9% 14% 593 63 1,432 2,088
Hawaii 6% 17% 14% 13% 44 52 1,286 1,382
Idaho 0% 43% 13% 15% 12 207 1,623 1,842
Illinois 41% 19% 8% 14% 785 767 3,806 5,358
Indiana 23% 17% 10% 11% 91 46 1,461 1,598
Iowa 28% 11% 12% 13% 41 40 1,577 1,658
Kansas 21% 26% 11% 12% 99 89 1,447 1,635
Kentucky 44% 8% 14% 16% 108 20 1,465 1,593
Louisiana 41% 28% 13% 22% 458 45 1,152 1,655
Maine 0% 31% 12% 12% 3 7 1,278 1,288
Maryland 24% 26% 6% 12% 369 68 1,049 1,486
Massachusetts 31% 49% 8% 11% 168 215 2,498 2,881
Michigan 34% 32% 9% 13% 542 126 3,663 4,331
Minnesota 33% 39% 8% 10% 41 60 1,678 1,779
Mississippi 43% 50% 14% 26% 621 19 977 1,617
Missouri 26% 16% 10% 12% 128 40 1,316 1,484
Montana 32% 30% 16% 16% 6 41 1,660 1,707
Nebraska 31% 28% 10% 11% 51 89 1,537 1,677
Nevada 31% 29% 8% 13% 78 291 1,110 1,479
New Hampshire 0% 18% 6% 6% 7 20 1,202 1,229
New Jersey 18% 27% 6% 9% 363 677 2,965 4,005
New Mexico 37% 35% 22% 27% 24 1,206 1,137 2,367
New York 35% 41% 9% 18% 1,128 1,907 5,781 8,816
North Carolina 31% 39% 9% 14% 575 85 2,256 2,916
North Dakota 0% 21% 13% 13% 2 22 1,535 1,559
Ohio 33% 25% 10% 13% 530 104 4,040 4,674
Oklahoma 44% 24% 15% 18% 142 75 1,614 1,831
Oregon 14% 32% 11% 13% 16 138 1,455 1,609
Pennsylvania 39% 36% 10% 13% 526 214 4,673 5,413
Rhode Island 21% 35% 10% 12% 43 130 1,156 1,329
South Carolina 41% 50% 11% 21% 445 16 911 1,372
South Dakota 42% 7% 15% 15% 14 13 1,748 1,775
Tennessee 29% 25% 15% 18% 273 23 1,306 1,602
Texas 24% 36% 10% 19% 553 3,209 3,721 7,483
Utah 22% 42% 7% 10% 11 188 1,718 1,917
Vermont 0% 51% 11% 11% 3 10 1,261 1,274
Virginia 14% 16% 11% 12% 355 80 1,375 1,810
Washington 19% 33% 13% 14% 46 85 1,467 1,598
West Virginia 55% 0% 18% 18% 27 14 1,683 1,724
Wisconsin 49% 48% 8% 11% 92 49 1,769 1,910
Wyoming 6% 4% 11% 13% 16 131 1,500 1,647
 
United States 32% 33% 10% 15%   12,893     19,361     98,222     130,476  

 

TABLE 2. National Estimates of the Proportions with each Characteristic Based on the CPS and the SIPP
  Variable   Total  
(%)
  Black  
(%)
  Hispanic  
(%)
  Children  
(%)
  Elderly  
(%)
1996 CPS Income below poverty 15 32 33 24 11
Receiving AFDC 4 13 9 11 0
Employer-provided health insurance   60 45 39 59 35
Work disability 8 10 6 0 27
1993 SIPP   Income below poverty 17 34 35 26 13
Receiving AFDC 5 15 13 12 0
Employer-provided health insurance 59 46 39 56 39
Work disability 7 9 6 1 27
  1. The SIPP only asks work disability questions of individuals under age 70. Therefore, for the percentage of elderly with a work related disability, these estimates reflect only those between the ages of 65 and 69.

 

  TABLE 3. Estimated State-Level Design Effects for the CPS and SIPP  
Characteristic   Design Effect  
Income below poverty 1.3
Receiving AFDC 1.2
Employer-provided health insurance   1.1
Work disability 1.0

 

  TABLE 4. Minimum and Maximum State Sample Sizes for Populations of Interest from the 1996 CPS and 1993 SIPP  
  Total Black Hispanic Children Elderly
CPS Minimum 1,161 (DC) 2 (ND) 7 (ME) 276 (DC) 59 (AK)
Maximum     12,904 (CA)     1,128 (NY)     5,601 (CA)     4,046 (CA)     1,212 (CA)  
SIPP    Minimum 104 (DC) 0 (*) 0 (*) 25 (DC) 14 (*)
Maximum 6,454 (CA) 435 (TX) 1,752 (CA) 1,990 (CA) 685 (CA)
* Multiple states.

 

TABLE 5. Number of States with the Sufficient Number of Completes to Provide Estimates of the Desired Level of Precision for Four Characteristics from the 1996 CPS and 1993 SIPP
  Variable   Total     Black     Hispanic     Children     Elderly  
CPS Income below poverty 51 24 19 51 51
Receiving AFDC 51 28 16 51 N/A
Employer-provided health insurance   51 25 20 51 50
Work disability 51 27 14 N/A 50
# of States Meeting Criteria for:
   All 4 characteristics 51 24 14 N/A N/A
   Only 3 characteristics -- 1 2 51 50
   Only 2 characteristics -- 2 3 -- --
   Only 1 characteristic -- 1 1 -- 1
   No characteristics 11 23 31 -- --
SIPPa Income below poverty 42 20 7 35 32
Receiving AFDC 35 20 7 35 N/A
Employer-provided health insurance   42 20 7 34 24
Work disability 40 20 6 N/A 9b
# of States Meeting Criteria for:
   All 4 characteristics 35 20 6 N/A N/A
   Only 3 characteristics 5 -- 1 34 9
   Only 2 characteristics 2 -- -- 1 15
   Only 1 characteristic -- -- -- -- 8
   No characteristics -- 22 35 7 10
  1. SIPP does not provide separate state identifiers for nine states. Therefore the maximum number of state that could meet the desired criteria is 42.
  2. The SIPP only provides a measure of work disability among the elderly for persons age 65 to 69. Therefore, we evaluated this variable in SIPP only for these ages. The criteria used was a confidence interval of 95 percent.

 

TABLE 6. Number of Selected Characteristics and Subgroup Combinations States Meeta
  March 1996 CPF 1993 SIPPb
  All Groups  
Max=18
  Excluding Hispanics  
Max=14
  All Groups  
Max=18
  Excluding Hispanics  
Max=14
Alabama 14 14 12 12
Alaska 8 8 NA NA
Arizona 14 10 12 9
Arkansas 14 14 7 7
California 18 14 18 14
Colorado 14 10 7 7
Connecticut 15 12 9 9
Delaware 14 14 3 3
District of Columbia   14 14 2 2
Florida 18 14 18 14
Georgia 14 14 13 13
Hawaii 10 10 3 3
Idaho 14 10 NA NA
Illinois 18 14 18 14
Indiana 10 10 13 13
Iowa 10 10 NA NA
Kansas 12 12 9 9
Kentucky 13 13 8 8
Louisiana 14 14 12 12
Maine 10 10 NA NA
Maryland 14 14 13 13
Massachusetts 18 14 9 9
Michigan 16 14 13 13
Minnesota 10 10 9 9
Mississippi 14 14 12 12
Missouri 14 14 13 13
Montana 10 10 NA NA
Nebraska 10 10 7 7
Nevada 14 10 3 3
New Hampshire 10 10 3 3
New Jersey 18 14 18 14
New Mexico 14 10 2 2
New York 18 14 18 14
North Carolina 14 14 14 14
North Dakota 10 10 NA NA
Ohio 15 14 14 14
Oklahoma 14 14 9 9
Oregon 13 10 9 9
Pennsylvania 18 14 14 14
Rhode Island 12 10 3 3
South Carolina 14 14 12 12
South Dakota 10 10 NA NA
Tennessee 14 14 13 13
Texas 18 14 18 14
Utah 14 10 7 7
Vermont 10 10 NA NA
Virginia 14 14 13 13
Washington 10 10 9 9
West Virginia 10 10 8 8
Wisconsin 11 11 8 8
Wyoming 12 10 NA NA
  1. The nine states for which the SIPP does not provide individual identifiers are: Alaska, Idaho, Iowa, Maine, Montana, North Dakota, South Dakota, Vermont, and Wyoming.
  2. The maximum number of combinations for all groups evaluated is 18 (three characteristics each for the elderly and children and four characteristics each for the total population, blacks and Hispanics). Removing Hispanics results in 14 combinations.

 

EXHIBIT 1. Number of Estimates for Each State from CPS Data
State Map: Always (All 18) - (8); All but Hispanic (All 14 w/o Hispanic, but not all 18) - (16); Frequently (More than 10, but not all) - (13); Rarely (10 or less) - (14)

 

EXHIBIT 2. Number of Estimates for Each State from SIPP Data
State Map: Always (All 18) - (6); All but Hispanic (All 14 w/o Hispanic, but not all 18) - (3); Frequently (more than 10, but not all) - (12); Rarely (Less than 10) - (21); Not available - (9)

 

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