2019 NSCH Table of State Sample Sizes

Appendix C – 2019 NSCH Table of State Sample Sizes

Appendix C
2019 NSCH - Estimated State Sample Sizes

State Sample Sizes
Alabama
Alaska
Arizona
Arkansas
California
Colorado
Connecticut
Delaware
District of Columbia
Florida
Georgia
Hawaii
Idaho
Illinois
Indiana
Iowa
Kansas
Kentucky
Louisiana
Maine
Maryland
Massachusetts
Michigan
Minnesota
Mississippi
Missouri
Montana
Nebraska
Nevada
New Hampshire
New Jersey
New Mexico
New York
North Carolina
North Dakota
Ohio
Oklahoma
Oregon
Pennsylvania
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Vermont
Virginia
Washington
West Virginia
Wisconsin
Wyoming
Total
Proportion by Strata

Oversampling
Rate
'k'
4.0
4.0
3.0
3.0
3.0
3.0
3.0
4.0
5.0
3.0
3.0
2.0
3.0
3.0
3.0
5.0
4.0
4.0
3.0
5.0
3.0
4.0
4.0
4.0
3.0
4.0
5.0
5.0
3.0
4.0
3.0
4.0
3.0
3.0
5.0
3.0
4.0
4.0
4.0
4.0
4.0
5.0
3.0
3.0
3.0
5.0
3.0
3.0
4.0
4.0
4.0

Proportion of
Households
with
Children from
2016 ACS
'P'
30%
26%
34%
32%
44%
39%
40%
33%
25%
33%
38%
33%
35%
38%
37%
26%
36%
30%
34%
23%
41%
38%
36%
40%
30%
35%
21%
27%
33%
32%
42%
25%
35%
35%
23%
39%
26%
34%
36%
33%
33%
25%
35%
40%
49%
24%
40%
38%
24%
36%
23%

Sampling
Variance
‘R’
1.05
1.04
1.00
0.99
1.04
1.00
1.00
1.04
1.01
0.98
1.02
0.98
1.00
0.99
1.00
0.99
1.06
1.03
1.01
0.98
1.00
1.06
1.04
1.04
0.98
1.06
1.01
1.02
1.00
0.99
1.02
1.04
1.00
0.99
1.01
0.99
1.03
1.03
1.03
1.06
1.05
1.03
1.00
1.03
1.05
1.03
1.00
0.99
1.00
1.04
0.99

Total
Sample
4076
4480
4078
5131
3236
2899
2886
3482
3639
4354
4222
4247
2950
3154
3209
2801
2882
3788
5140
3355
2815
2598
2626
2004
5582
3196
3790
2986
4287
3175
2906
5238
3709
3719
3352
3099
4624
2821
2740
3540
3776
3082
3548
4112
2211
3171
2767
2841
4926
2340
4433
180,022

Stratum 1
Sample
(Admin Flag
for HHLD
w/Children)
2549
2398
2353
2802
2219
1797
1894
2343
2343
2646
2680
1458
1735
1972
2025
1713
1948
2266
3144
1953
1862
1799
1798
1414
3087
2116
1991
1834
2484
2012
1897
2662
2189
2223
1882
1983
2576
1837
1864
2179
2531
1831
2186
2632
1573
1804
1800
1763
2330
1565
2218
108,163
60%

Stratum 2a
Sample
(Admin Flag
for HHLD
w/o Children)
1527
2081
1725
2328
1017
1103
992
1139
1296
1708
1542
2789
1215
1182
1185
1088
934
1522
1996
1402
953
799
828
589
2495
1080
1799
1152
1802
1163
1009
2576
1520
1496
1470
1116
2047
984
876
1362
1245
1251
1362
1480
638
1367
967
1078
2596
775
2215
71,859
40%

Appendix C
Calculations for State Sample Sizes
The oversampling rate (k) was calculated to maximize the sample from Stratum 1 without increasing the
variance (R) too much beyond that of a proportional stratified design of a similar cost.
(P) is the proportion of households with children based on the 2016 ACS audit 1.
The portion of the sample coming from each stratum was calculated using the oversampling rate (k) and
the proportion of all households in each of the sampling strata (W1 and W2a). Address valid rates, child
prevalence rates, and Screener and Topical returns rates were estimated by state and stratum primarily
using 2018 response outcomes. A national total sample size of approximately 180,000 was determined
based on budget, which we expect will produce 516 Topical interviews per state. The expected number of
interviews along with the 2018 response information was used to calculate stratum sample sizes (n1 and
n2a) in each state.
For example, in Alabama:
The oversampling rate (k) was recalculated to be 4.0, for an R = 1.05. Of the 2016 ACS households
eligible for NSCH sampling, 29.4% would be put in Stratum 1 (W1) and 70.6% would be put in Stratum
2a (W2a).
The portion of the sample coming from Stratum 1 was estimated to be (k*W1) / (W2a + k*W1) = 62.5%
and the portion of the sample from Stratum 2a was 37.5%.
We can expect a completed Topical from 92.2% (Valid) * 35.9% (Screener) * 76.9% (Children) * 73.9%
(Topical) = 18.8% of addresses in Stratum 1 and 75.1% (Valid) * 42.4% (Screener) * 11.2% (Children) *
67.3% (Topical) = 2.4% of addresses in Stratum 2a.
Since we expect to get 516 Topicals per state, we can get the state sample size (n) by evaluating the
following:
(n * Portion of the sample from Stratum 1 * Stratum 1 completed Topical rate) + (n * Portion of the
sample from Stratum 2a * Stratum 2a completed Topical rate) = 516.
Within rounding, it then follows that n = 516 / (62.5% * 18.8% + 37.5% * 2.4%) = 4076. Now n1 = 4076
* 62.5% = 2549 and n2a = 4076 * 37.5% = 1527.

1

Before mailout, this will be updated with the 2017 ACS.