OMB NDTS 2012 Supporting Statement PART B

SUPPORTING STATEMENT
National Drug Intelligence Center Drug Threat Assessment Survey
OMB No. 1105-0071

B. COLLECTION OF INFORMATION EMPLOYING STATISTICAL METHODS

1. The potential respondent universe is the 8,420 municipal police departments and county
sheriff departments (in states where sheriffs have drug enforcement responsibilities) with 10
or more full-time equivalent sworn officers identified in the 2008 Census of State and Local
Law Enforcement Agencies conducted by the United States Department of Justice Bureau of
Justice Statistics. The existing sample of 2,807 agencies was drawn to ensure that the sample
is representative at the state level. Please see the attached table for a breakdown of the
sample by stratum. The response rate for 2011 was 85 percent and a response rate of 85
percent or higher was achieved from 2003 through 2010 using a similar collection form.
Documentation of the sample plan is attached.
2. The sample was a systematic sample by stratum (state) with a random start within each
stratum. Law enforcement agencies with 75 or more full-time equivalent sworn officers and
state drug enforcement agencies were sampled with certainty. Local law enforcement
agencies with 10 or more and less than 75 full-time equivalent sworn officers were selected
randomly within each state stratum. The degree of accuracy is indicated by coefficient of
variation of less than 3% for regions and less than 5% for states on the number of full-time
equivalent sworn officers (size of agency).
3. NDIC Collection Management Unit personnel will be assigned to identify and verify
appropriate survey recipients at sample agencies and conduct follow-up activities for nonresponding agencies. A weighting adjustment will be made to correct for agency
nonresponse. The sample size will comprise 33 percent of the respondent universe.
4. No tests of procedures will be conducted.
5. Carma Hogue (301-763-4882) and Bac Tran (301-763-1937) of the U.S. Census Bureau were
consulted on statistical aspects of the design. The U.S. Census Bureau will not actually
collect and/or analyze the information for NDIC.

Documentation for the 2012 National Drug Threat Survey Sample Design

The National Drug Threat Survey (NDTS) is sponsored and conducted by the National Drug
Intelligence Center (NDIC). The U.S. Census Bureau selects the sample and consults on
statistical issues. The frame for the 2012 NDTS sample is based on the 2007 Law Enforcement
Management and Administrative Statistics (LEMAS) Survey which is conducted every 3 to 4
years by the Bureau of Justice Statistics. This frame, comprised of 8,420 units, does not include
the 69 state agencies that are external certainties and will be added to the sample. Table 1
contains a list of those state agencies. Besides stratification by state, the design also has nine
domains called regions: Florida/Caribbean, Great Lakes, Mid-Atlantic, New York/New Jersey,
New England, Pacific, Southeast, Southwest, and West Central. Table 2 contains a list of the
states included in each region.
Sample Design
Eligible Units
Only municipal police departments and county sheriffs are eligible for inclusion in the sample.
Sheriffs in Alaska, Connecticut, District of Columbia, Delaware, Hawaii, Massachusetts,
Pennsylvania, Rhode Island, and Virginia are ineligible. Units need to have at least 10 full-time
equivalents (FTE) to be in-scope.
Preliminary Sample Selection
The NDIC identified three requirements for the 2012 NDTS sample:
1. The coefficient of variation (CV) on each state’s FTE estimate should be between 3% and
5%,
2. Units with an FTE of 75 or greater are certainties, and
3. The total sample size should not exceed 3,200 units.
In addition to those three conditions, the frame was divided into 51 strata, one per state and one
for the District of Columbia. Then, a simple random sample (SRS) was selected from the target
frame, i.e. units satisfying 10 ≤ FTE < 75.
Final Sample Selection
The results of the preliminary sample selection yielded some states with CVs greater than 5%.
To correct that problem, a sub-stratification technique was applied by modifying the certainty
condition. The certainty criteria were not modified for all states. A list of the states that were
modified can be found in Table 3. States where the certainty criteria were not modified used an
FTE of 75 as the cutoff value. Further details about the number of units selected per sub-stratum
can be found in Table 4. The sample size is 2,738 units, a decrease from previous sample sizes.
Table 5 contains more detailed information about the number of units included in the sample as
well as CV estimates at the state level (CV estimates at the region level are in Table 6). After
including the 69 state agency units, the final sample size is 2,807 units, a decrease from previous
samples.

The sampled units along with their sampling weights are in an Excel workbook entitled
NDTS2012_sample.xslx on the sheet labeled Sample. The file layout for the sample is in the
same workbook, on the sheet entitled Layout.
Estimation
All variance estimates were performed using the SAS procedure SURVEYMEANS.
Let

be the estimate of the total FTE for state g. The variance of the total FTE for state g,
, is estimated using the following formula:
(1)

where
is the sample variance of state g
is the number of samples units for state g
is the total number of units on the frame for state g
The coefficient of variation for state g,

, is estimated as follows:
(2)

The states in Table 3 were sub-stratified by a different cutoff value for FTE. Therefore, the
variance of each state in Table 3 is a stratified variance estimate. The variance is given by:
(3)
where k is the sub-strata in state g.

Table 1. List of State Agencies (External Certainties)
State Agency
Alaska State Troopers
Alabama Bureau of Investigation
Arkansas State Police
Arizona Department of Public Safety
California Highway Patrol
California Department of Justice
Colorado State Patrol
Connecticut State Police
Delaware State Police
Florida Department of Law Enforcement
Florida Highway Patrol
Georgia State Patrol
Guam Customs and Quarantine Agency
State of Hawaii, Department of Public Safety
Iowa Division of Narcotics Enforcement
Idaho State Police
Illinois State Police
Indiana State Police
Kansas Bureau of Investigation
Kansas Highway Patrol
Kentucky State Police - East Region
Louisiana State Police
Massachusetts State Police Department
Maryland State Police
Maine Drug Enforcement Agency
Maine State Police
Michigan State Police
Minnesota Department of Public Safety
Minnesota State Patrol
Missouri State Highway Patrol
Drug Enforcement Administration
Mississippi Bureau of Narcotics
Montana Division of Criminal Investigation
Montana Highway Patrol
North Carolina Alcohol Law Enforcement Division
North Carolina State Bureau of Investigation
North Carolina State Highway Patrol
North Dakota Bureau of Criminal Investigation
Nebraska State Patrol

State
AK
AL
AR
AZ
CA
CA
CO
CT
DE
FL
FL
GA
GU
HI
IA
ID
IL
IN
KS
KS
KY
LA
MA
MD
ME
ME
MI
MN
MN
MO
MP
MS
MT
MT
NC
NC
NC
ND
NE

City
Anchorage
Montgomery
Little Rock
Phoenix
Sacramento
Sacramento
Denver
Middletown
Bridgeville
Tallahassee
Tallahassee
Dalton
Barrigada
Honolulu
Des Moines
Meridian
Springfield
Indianapolis
Great Bend
Topeka
Frankfort
Baton Rouge
Watertown
Columbia
Portland
Houlton
Lansing
St. Paul
Golden Valley
Jefferson City
Saipan
Jackson
Helena
Great Falls
Raleigh
Raleigh
Winston-Salem
Bismarck
Lincoln

State Agency

State

New Hampshire State Police
New Hampshire Attorney General's Drug Task Force
New Jersey State Police
New Mexico State Police
Nevada Department of Public Safety, Investigation Division
New York State Police
Ohio State Highway Patrol
Ohio Bureau of Criminal Identification & Investigation
Oklahoma Highway Patrol
Oklahoma State Bureau of Narcotics & Dangerous Drugs Control
Oregon State Police
Pennsylvania Office of Attorney General
Pennsylvania State Police
Puerto Rico Police Department
Rhode Island Department of Attorney General
Rhode Island State Police
South Carolina Highway Patrol
South Carolina State Law Enforcement Division
South Dakota Division of Criminal Investigation
Tennessee Bureau of Investigation
Texas Department of Public Safety
Utah Department of Public Safety
Virginia State Police
Vermont State Police
Washington State Patrol
Wisconsin State Patrol
Wisconsin Department of Justice
West Virginia State Police
Wyoming Division of Criminal Investigation
Wyoming Highway Patrol

NH
NH
NJ
NM
NV
NY
OH
OH
OK
OK
OR
PA
PA
PR
RI
RI
SC
SC
SD
TN
TX
UT
VA
VT
WA
WI
WI
WV
WY
WY

City
Concord
Bedford
West Trenton
Santa Fe
Carson City
Latham
Columbus
London
Oklahoma City
Oklahoma City
Salem
Lemoyne
Harrisburg
San Juan
Providence
North Scituate
Columbia
Columbia
Sioux Falls
Nashville
Austin
Salt Lake City
Richmond
Waterbury
Olympia
Milwaukee
Milwaukee
South Charleston
Cheyenne
Cheyenne

Table 2. Definition of Organized Crime Drug Enforcement Task Force (OCDETF) Regions
OCDETF Region
Florida/Caribbean

Great Lakes

Mid-Atlantic

New York/New
Jersey

New England

Pacific

Southeast

State
FL
PR
IN
IL
KY
MI
MN
OH
WI
DE
DC
MD
PA
VA
WV
NJ
NY
CT
MA
ME
NH
RI
VT
AK
CA
GU
HI
ID
MP
NV
OR
WA

AR

(All counties not in West Central Region)

(All counties not in Southwest Region)

OCDETF Region

State
AL
GA
LA
MS
NC
SC
TN
AZ
CA

Southwest

(counties of: Imperial, Los Angeles Orange, Riverside, San
Bernardino, San Diego, San Luis Obispo, Santa Barbara,
Ventura)

NM
OK
TX
CO
IA

IL

West Central
KS
MO
MT
ND
NE
SD
UT
WY

(counties of Alexander, Bond, Calhoun, Clark, Clay,
Clinton, Crawford, Cumberland, Edwards, Effingham,
Fayette, Franklin, Gallatin, Hamilton, Hardin, Jackson,
Jasper, Jefferson, Jersey, Johnson, Lawrence, Madison,
Marion, Massac, Monroe, Perry, Pope, Pulaski, Randolph,
Richland, Saline, St. Clair, Union, Wabash, Washington,
Wayne, White, Williamson)

Table 3. List of States Requiring Stratum Modification
Strata
02
04
05
08
10
13
16
18
20
25
27
28
30
32
35
40
42
45
46
49
51

State
AK
AR
CA
DE
FL
ID
IA
KY
ME
MS
MT
NE
NH
NM
ND
RI
SD
UT
VT
WV
WY

Table 4. Final Sample Selection by Strata
State

Strata

AL

01

AK

02

AZ

03

AR

04

CA

05

CO

06

CT

07

DE

08

DC

09

FL

10

Substratum
10 ≤ FTE < 75
FTE ≥ 75
10 ≤ FTE < 20
FTE ≥ 20
10 ≤ FTE < 75
FTE ≥ 75
10 ≤ FTE < 20
20 ≤ FTE < 40
40 ≤ FTE < 50
50 ≤ FTE < 100
FTE ≥ 100
10 ≤ FTE < 20
20 ≤ FTE < 40
40 ≤ FTE < 60
60 ≤ FTE < 80
80 ≤ FTE < 100
100 ≤ FTE < 150
150 ≤ FTE < 200
200 ≤ FTE < 250
250 ≤ FTE < 300
FTE ≥ 300
10 ≤ FTE < 75
FTE ≥ 75
10 ≤ FTE < 75
FTE ≥ 75
10 ≤ FTE < 20
20 ≤ FTE < 50
FTE ≥ 50
10 ≤ FTE < 75
FTE ≥ 75
10 ≤ FTE < 20
20 ≤ FTE < 40
40 ≤ FTE < 60
60 ≤ FTE < 80
80 ≤ FTE < 100
100 ≤ FTE < 200
200 ≤ FTE < 300
FTE ≥ 300

Sampling
Weight
3.10
1.00
1.57
1.00
7.11
1.00
6.60
3.45
7.00
1.33
1.00
17.00
7.55
8.60
8.00
6.60
3.50
3.29
2.50
1.22
1.00
4.89
1.00
3.08
1.00
1.29
1.33
1.00
1.00
13.20
6.27
8.00
5.67
7.50
1.30
1.36
1.00

Number
of Units
51
24
7
4
9
27
10
11
1
9
12
4
11
5
5
5
10
7
4
9
26
18
27
24
25
7
3
5
0
1
5
11
4
3
2
30
14
31

State

Strata

GA

11

HI

12

ID

13

IL

14

IN

15

IA

16

KS

17

KY

18

LA

19

ME

20

MD

21

MA

22

MI

23

MN

24

MS

25

MO

26

Substratum
10 ≤ FTE < 75
FTE ≥ 75
10 ≤ FTE < 75
FTE ≥ 75
10 ≤ FTE < 20
20 ≤ FTE < 40
FTE ≥ 40
10 ≤ FTE < 75
FTE ≥ 75
10 ≤ FTE < 75
FTE ≥ 75
10 ≤ FTE < 20
20 ≤ FTE < 40
40 ≤ FTE < 60
FTE ≥ 60
10 ≤ FTE < 75
FTE ≥ 75
10 ≤ FTE < 20
20 ≤ FTE < 40
40 ≤ FTE < 100
FTE ≥ 100
10 ≤ FTE < 75
FTE ≥ 75
10 ≤ FTE < 20
FTE ≥ 20
10 ≤ FTE < 75
FTE ≥ 75
10 ≤ FTE < 75
FTE ≥ 75
10 ≤ FTE < 75
FTE ≥ 75
10 ≤ FTE < 75
FTE ≥ 75
10 ≤ FTE < 20
20 ≤ FTE < 40
40 ≤ FTE < 60
60 ≤ FTE < 100
FTE ≥ 100
10 ≤ FTE < 75
FTE ≥ 75

Sampling
Weight
7.79
1.00
1.00
5.00
3.33
1.00
12.56
1.00
3.02
1.00
4.50
1.82
2.00
1.00
2.51
1.00
13.60
5.88
2.86
1.00
9.33
1.00
4.90
1.00
9.60
1.00
4.73
1.00
4.70
1.00
2.49
1.00
7.44
4.20
5.50
2.00
1.00
3.76
1.00

Number
of Units
33
64
0
4
5
6
18
32
50
62
24
18
11
6
14
39
15
5
8
7
7
12
49
10
36
5
22
48
40
53
41
74
16
9
10
4
7
9
59
28

State

Strata

MT

27

NE

28

NV

29

NH

30

NJ

31

NM

32

NY

33

NC

34

ND

35

OH

36

OK

37

OR

38

PA

39

RI

40

SC

41

SD

42

Substratum
10 ≤ FTE < 20
20 ≤ FTE < 40
40 ≤ FTE < 85
FTE ≥ 85
10 ≤ FTE < 20
20 ≤ FTE < 40
FTE ≥ 40
10 ≤ FTE < 75
FTE ≥ 75
10 ≤ FTE < 20
20 ≤ FTE < 40
40 ≤ FTE < 80
FTE ≥ 80
10 ≤ FTE < 75
FTE ≥ 75
10 ≤ FTE < 20
20 ≤ FTE < 40
40 ≤ FTE < 100
FTE ≥ 100
10 ≤ FTE < 75
FTE ≥ 75
10 ≤ FTE < 75
FTE ≥ 75
10 ≤ FTE < 20
20 ≤ FTE < 40
FTE ≥ 40
10 ≤ FTE < 75
FTE ≥ 75
10 ≤ FTE < 75
FTE ≥ 75
10 ≤ FTE < 75
FTE ≥ 75
10 ≤ FTE < 75
FTE ≥ 75
FTE ≥ 10
10 ≤ FTE < 75
FTE ≥ 75
10 ≤ FTE < 20
20 ≤ FTE < 40
FTE ≥ 40

Sampling
Weight
5.60
1.75
1.50
1.00
7.00
3.00
1.00
10.00
1.00
5.44
2.86
1.22
1.00
7.14
1.00
8.33
3.71
1.20
1.00
43.83
1.00
6.00
1.00
4.50
1.67
1.00
6.00
1.00
2.55
1.00
2.49
1.00
6.05
1.00
1.00
3.66
1.00
3.25
1.43
1.00

Number
of Units
5
4
6
2
4
5
11
2
10
9
7
9
2
51
80
3
7
10
7
6
62
41
67
2
6
5
71
46
53
12
35
17
65
19
36
29
32
4
7
5

State

Strata

TN

43

TX

44

UT

45

VT

46

VA

47

WA

48

WV

49

WI

50

WY

51

Substratum
10 ≤ FTE < 75
FTE ≥ 75
10 ≤ FTE < 75
FTE ≥ 75
10 ≤ FTE < 20
20 ≤ FTE < 40
40 ≤ FTE < 100
100 ≤ FTE < 200
FTE ≥ 200
10 ≤ FTE < 20
20 ≤ FTE < 40
40 ≤ FTE < 50
FTE ≥ 50
10 ≤ FTE < 75
FTE ≥ 75
10 ≤ FTE < 75
FTE ≥ 75
10 ≤ FTE < 20
20 ≤ FTE < 40
40 ≤ FTE < 80
FTE ≥ 80
10 ≤ FTE < 75
FTE ≥ 75
10 ≤ FTE < 20
20 ≤ FTE < 40
40 ≤ FTE < 85
FTE ≥ 85

Sampling
Weight
4.71
1.00
17.07
1.00
11.00
6.00
2.00
1.43
1.00
4.20
1.71
1.00
1.00
6.40
1.00
3.26
1.00
5.17
2.33
1.80
1.00
3.72
1.00
4.67
2.75
1.13
1.00

Number
of Units
38
36
27
99
3
4
6
7
2
5
7
1
1
10
25
39
26
6
9
5
4
54
32
3
4
8
2

Table 5. Detailed Sample Design Information by State
NOTE: (a) = (b) + (c), (e) = (c) + (d)

Strata

01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33

State

AL
AK
AZ
AR
CA
CO
CT
DE
DC
FL
GA
HI
ID
IL
IN
IA
KS
KY
LA
ME
MD
MA
MI
MN
MS
MO
MT
NE
NV
NH
NJ
NM
NY

Total
Number of
Units on the
Frame

Number of
Non-certainty
Units on the
Frame

Number of
Certainty
Units

Number of
Non-certainty
Units Sampled

Total
Sample
Size

(a)

(b)

(c)

(d)

(e)

182
17
91
135
372
115
99
18
1
288
321
4
63
452
211
127
113
142
161
85
70
267
290
200
154
250
46
54
30
82
444
70
325

158
16
64
123
346
88
74
13
0
257
257
0
58
402
187
118
98
140
112
84
48
227
249
184
145
222
44
50
20
80
364
63
263

24
1
27
12
26
27
25
5
1
31
64
4
5
50
24
9
15
2
49
1
22
40
41
16
9
28
2
4
10
2
80
7
62

51
10
9
31
60
18
24
10
0
69
33
0
24
32
62
40
39
25
12
45
5
48
53
74
30
59
15
16
2
25
51
20
6

75
11
36
43
86
45
49
15
1
100
97
4
29
82
86
49
54
27
61
46
27
88
94
90
39
87
17
20
12
27
131
27
68

CV

3.85%
4.06%
3.71%
3.77%
1.33%
2.08%
3.75%
4.60%
0.00%
1.88%
2.75%
0.00%
4.78%
3.68%
3.64%
3.06%
3.74%
4.49%
3.08%
4.73%
3.12%
3.23%
3.61%
4.11%
3.11%
3.28%
3.92%
4.93%
0.27%
3.79%
2.96%
4.22%
2.35%

Strata

State

34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51

NC
ND
OH
OK
OR
PA
RI
SC
SD
TN
TX
UT
VT
VA
WA
WV
WI
WY

Total

Total
Number of
Units on the
Frame

Number of
Non-certainty
Units on the
Frame

Number of
Certainty
Units

Number of
Non-certainty
Units Sampled

Total
Sample
Size

(a)

(b)

(c)

(d)

(e)

313
24
472
147
104
412
36
138
28
215
560
81
35
89
153
65
233
36

246
19
426
135
87
393
20
106
23
179
461
79
33
64
127
61
201
34

67
5
46
12
17
19
16
32
5
36
99
2
2
25
26
4
32
2

41
8
71
53
35
65
20
29
11
38
27
20
12
10
39
20
54
15

108
13
117
65
52
84
36
61
16
74
126
22
14
35
65
24
86
17

8,420

7,248

1,172

1,566

2,738

CV

3.35%
3.59%
3.31%
3.50%
3.30%
3.24%
3.48%
4.05%
4.60%
3.77%
3.20%
3.81%
4.47%
2.49%
2.21%
3.17%
3.73%
3.69%

Table 6. Estimated CVs by Region
Region
Florida
Great Lakes
Mid-Atlantic
New England
New York/New Jersey
Pacific
Southeast
Southwest
West Central

CV
1.88%
1.72%
1.57%
1.88%
1.86%
2.01%
1.35%
2.58%
2.09%