Overview of Changes from Previous Surveys |
| Sample Design. The MECS has increased its sample size by roughly 40 percent since the 1991
survey, increasing the designed sample size from 16,054 establishments to 22,922. This
increase in size and change in sampling criteria required a departure from using the
Annual Survey of Manufactures (ASM) as the MECS sampling frame. For 1994, establishments
were selected directly from the 1992 Census of Manufactures (CM) mail file, updated by
1993 ASM. |
| Sample Frame Coverage. The coverage in the 1994 MECS is 98 percent of the manufacturing population
as measured in total payroll. The sampling process itself provided that level of coverage,
and no special adjustments were used to increase it. The 1991 survey had identical
coverage, whereas the 1988 survey was statistically adjusted to cover 100 percent of the
population. Therefore, many of the potential sources of bias that pertained to the 1988
survey estimates are not relevant to either the 1991 or 1994 survey. Because of the
difference in sample coverage, care must be exercised when comparing absolute quantities
among the three surveys--small differences might be correctly attributable to coverage
rather than real change. |
| New Industry Estimates. The nearly 7,000 increase in the number of establishments sampled has
allowed EIA to publish separate estimates for 52 industries and industry groups, in
addition to the 20 larger major groups (2-digit SIC). In 1991, there were 42 industries
and industry groups published; and in 1988, the sample design permitted only 10 industries
for which separate estimates were publishable beyond the 20 major groups. Also, for the
first time, this latest report presents estimates relating to the number of manufacturing
establishments. |
| Additional Data Items for Improved
Estimation. In 1991, EIA recognized a potential for
overestimating energy source quantities in industries that produce and sell energy
sources; it corrected for such overestimation by collecting energy shipments from sample
establishments. The correction is required when a manufacturer uses an energy source as an
input to a process (i.e, feedstock), produces another energy source as a result of that
process, and then sells or transfers the produced energy source to another establishment.
The quantity of the receipt in the second establishment would duplicate the feedstock use
in the first. Part of the solution has been to estimate consumption in petroleum
refineries differently from other industries (see section entitled "Feedstocks and
Offsite-Produced Fuel at Petroleum Refineries" in this appendix). To correct the
problem for other industries, the MECS, in 1991, began collecting shipments offsite of
energy sources produced onsite (see "Development of the Data File" in this
appendix). EIA has continued to correct for energy shipments from manufacturing
establishments in 1994. In addition, estimates of energy shipments appear in Table A1,
First Use of Energy, of this report. |
| New Data Collection Sections. Survey collection forms now include sections on natural gas industry
restructuring— service rates of natural gas purchases; supply, transportation, and
other costs associated with non-local distribution company natural gas
purchases—actual fuel switching occurring between natural gas and residual fuel oil,
types of cogeneration technology in use by manufacturers, square footage of manufacturing
floorspace, and energy management activities (sponsored by electric utility; self; and
Federal, State, and local governments). As a one-time collection of establishment
activities, EIA investigated the methods that manufacturers most commonly used to
purchase, and to make modifications to, electric motor systems. |
| New Geography Level. In part,
the nearly 7,000-establishment increase in sample size provides for reliable estimation of
energy consumption at the nine Census divisions (see glossary for a definition of Census
division and Appendix E for a division-level map). |
The SIC manual contains a hierarchial classification system that
groups establishments according to their primary economic activities. This system divides
the manufacturing sector (referred to as "manufacturing division" in the SIC
manual) into 20 major industrial groups that are relatively homogeneous with respect to
primary output. Each of these major industrial groups is assigned a two-digit code. The
two-digit codes for the manufacturing sector range from SIC 20, Food and Kindred Products,
through SIC 39, Miscellaneous Manufacturing Industries. Each major group is subdivided
into three-digit groups, which are further divided into four-digit industries. For
example, SIC 20 includes SIC 201, Meat Products, which, in turn, is subdivided into SIC
2011, Meat Packing Plants; SIC 2012, Sausages and Other Prepared Meat Products; SIC 2016,
Poultry Dressing Plants; and SIC 2017, Poultry and Egg Processing.
The SIC category is the single most important classification
variable in the MECS data system, both for selecting the survey sample and analyzing the
tabulated data. The categories of primary interest for the MECS are the 20 major
industrial groups (SIC 20 through 39) and the 52 three- and four-digit industries that
consumed the most energy, demonstrated high growth, or had a special programmatic
interest. A description of these 20 major industrial groups and 52 industry groups and
industries appears in Appendix F of this report.
The 1994 MECS, as well as the 1988 and 1991 surveys, used the SIC
classification system that is presented in the 1987 edition of the SIC manual. The 1985
MECS was based on the 1972 SIC manual. For the most part, the revisions were minor and had
a negligible effect on the MECS estimates. However, there were some revisions that would
affect comparisons between 1985 and subsequent years.
Among the more significant revisions was the one concerning the way
certain petrochemical plants were classified for the 1988, 1991, and 1994 MECS, as opposed
to the 1985 survey. If the primary product of a petrochemical plant in 1985 was a
liquefied petroleum gas (LPG), the plant was classified in SIC 2911 as Petroleum Refining,
regardless of how the LPG was produced. For the later survey years (including the 1994
survey), the establishment was classified in SIC 2911 only if the LPG was produced by a
refinery process. If the LPG was produced by a chemical process, the establishment
was classified as an organic chemical industry (SIC 2865 or 2869).
Thus, when comparing the estimates for SICs 2911, 2865, and 2869 between the 1985 and
later MECS reports, the reader is cautioned to take the classification differences into
account.2
The Sampling Frame and Its Relationship to the
Manufacturing Sector
As mentioned in the Introduction to this appendix, the Census Bureau
serves as the collecting and compiling agent for the MECS. In addition to the MECS, a
major responsibility of the Manufacturing and Construction Division of the Census Bureau
is to conduct the Census of Manufactures (CM) and the Annual Survey of Manufactures (ASM).
MECS uses those surveys to construct a sampling frame, as well as to provide economic data
for establishments common to both systems.
Census of Manufactures
The CM is conducted for years ending in "2" or
"7" (for example, 1992) and obtains economic data for the complete universe of
approximately 380,000 manufacturing establishments in the United States. For the purposes
of data collection, the manufacturing universe is divided into two major subsets as
follows.
1. Small Single-Establishment Companies Not Sent
a Report Form. Generally, companies with fewer than five
employees are excused from filing a CM report. Those with 5 through 20 employees are
excused or sent a report form based on the magnitude of their annual payroll and shipments
data. In 1992, approximately 143 thousand establishments were excused from filing due to
this criterion.
2. Establishments Sent a Report Form. All companies with 20 or more employees are mailed a CM report form. In 1992,
approximately 237 thousand establishments fell into this subset of the CM manufacturing
universe, which represents all multi-establishment firms and single-establishment firms
with payrolls above a pre-determined cutoff level.
Annual Survey of Manufactures
The ASM is conducted during non-CM years to provide estimates of
economic characteristics for the universe of manufacturing establishments. As with the CM,
the ASM contains two components. The first component is the mail portion, a probability
sample of manufacturing establishments selected from the list of establishments that are
sent the CM report form (see above). Those establishments are weighted so that they
represent the mail portion of the CM universe. The second component of the ASM is the
nonmail portion of the CM. These small establishments are not sent an ASM questionnaire,
but their contribution to economic statistics is estimated based on selected information
obtained annually from other Federal agencies. For the 1994 ASM, approximately 55 thousand
questionnaires were mailed to manufacturing establishments that had been selected from an
updated 1992 CM mail file.
Manufacturing Energy Consumption Survey
In 1994, the MECS improved its sampling procedure. For the first
time, the survey sample was drawn directly from the updated 1992 CM mail file, rather than
subsampled from the ASM mail file. While this change in sampling frame has no effect on
the coverage of the manufacturing universe by the MECS—sample establishments, when
weighted, still cover 98 percent of the manufacturing universe, as measure by total
payroll—this improvement permits the MECS to target directly those industries that
are of significant interest to data users, as well as to control subnational sampling (see
Sample Design section in this appendix).
3
Of the 239,000 eligible establishments in the CM mail file, 22,922 were selected for the
1994 MECS sample, of which 22,173 were mailed a questionnaire and 749 were identified as
out of scope (e.g., out of business).
Coverage Differences Between MECS 1988 and 1985,
1991, and 1994
Due to an adjusted coverage difference between the 1988 survey
design and 1985, 1991 and 1994 designs, the coverage of manufacturing estimates varied
slightly from the 1988 survey to the other surveys. Therefore, EIA urges that comparisons
of estimates produced from these surveys and analysis of trends be done with caution.
The 1994 MECS estimates cover 98 percent of the manufacturing sector
as measured by total payroll. The 2 percent of the payroll not covered is known to be
represented by a subgroup of relatively small but numerous manufacturing establishments.
When taken as a whole, they account for roughly 2 percent of a number of different
economic measures, including energy consumption. Because of the cost and difficulty of
accurately surveying this subgroup, it was excluded from the survey and, thus, from the
estimates presented in this report.
In contrast, the 1988 MECS estimates represent the entire
manufacturing sector. Small establishments excluded from the other MECS surveys were
accounted for by means of a population adjustment factor, applied to each
establishment’s sampling weight (by stratum) after the sample was drawn. Coverage
adjustment was necessary for the 1988 survey because the coverage of the population had
degraded over time, and Census procedures for population updates could not entirely
compensate for the coverage loss. Also, EIA wanted to retain the active portion of the
1985 sample, rather than select an entirely new sample. This method meant that
establishments had to be classified according to very specific definitions. For example,
establishments that had ceased operation since 1985 had to be distinguished from those
that merely underwent a change of ownership. To counteract the coverage loss, as well as
the operational errors that might have occurred while maintaining a sample built in this
way, a ratio adjustment was selected to adjust selected MECS economic estimates to control
totals from the 1987 Census of Manufactures. By necessity, that adjustment also included
the portion of the manufacturing sector that was not originally intended for estimation,
the 2 percent of certain economic measures represented by the smallest establishments.4 The 1994
and other MECS surveys did not use an adjustment factor because: (1) there was no readily
available population adjustment for 1991 estimates, and (2) the relative simplicity of the
sample design yielded fewer operational errors.
The 1985 estimates excluded the smallest establishments from
coverage. That exclusion tends to make 1985 coverage comparable with the 1991 and 1994
coverages. Due to Census’ updating procedures that were in place during the 1985
survey, the coverage might have been slightly less than the 98 percent of the 1991 and
1994 surveys, but exact estimates of coverage are difficult to estimate. Therefore,
caution must be exercised by readers who wish to compare 1985, 1988, 1991, and 1994
estimates.5
Sample
Design
Sample Size
The expected size of the MECS sample was 23,000 establishments.
Because of the randomness of sampling, the actual sample size differed. Of the
approximately 239 thousand eligible establishments, exactly 22,922 establishments were
selected, of which 22,173 were mailed a questionnaire.
In selecting the sample, the MECS had
specific target criteria by SIC stratum and Census division. The targeted sampling errors
in terms of relative standard errors (RSE) for the MECS sample were:
- zero for total energy expenditures in heavy energy-consuming
industries, with all eligible establish-ments being selected, resulting in a census of
these industries (see text box);
- no more than 3 percent for total energy expenditures in
nonfuel-intensive SIC industries (2819, 2821, and 2869); and
- no more than 5 percent for total energy expenditures in each of the
remaining groups and industries.
Because data users requested more precise subnational
estimates (i.e., four Census regions and nine divisions), the 1994 MECS sample was highly
controlled at sub-national levels, as defined by SIC and Census divisions (see Table B1 in
this appendix). This represented a change from previous samples.
Not all industries or industry groupings were controlled at
the Census-division level. To target each industry and Division, a much larger sample,
exceeding the expected 23,000 establishment target set for the 1994 MECS, would have been
required. Instead, only 150 cells (as defined by SIC and Census division) were controlled.
These cells represent the industries-division groupings that account for the largest
expenditures for energy. A detailed sampling table is provided in Table B1 of this
appendix. In addition to the 150 controlled cells, the table also shows the cell totals
for those industries for which a census of all establishments was included in the sample.
The major purpose of increasing the sample size was to be able to
produce separate energy estimates for more industries than before, as well as to produce
more precise sub-national estimates. The first two surveys—in 1985 and
1988—published estimates for the 20 two-digit major groups that comprise
manufacturing and 10 four-digit industries. Those 10 four-digit industries were the most
energy-consuming in manufacturing. The 1991 MECS published 40 four-digit industries, 2
three-digit industry groups, and 20 two-digit major groups. The 1994 MECS has 49
four-digit industries, 3 three-digit industry groups, and 20 two-digit major groups. These
industry additions come from three groups: (1) industries not in the top 10, but with high
energy consumption; (2) certain high-growth industries, such as computers and medical
instruments; and (3) industries for which there are identifiable policy interests or
conservation opportunities.
reliability of existing estimates, especially among the major groups (two-digit SICs). For
example, SIC 20 in the current sample design includes eight four-digit industries for
which estimates were publishable. Previously, in the 1985 and 1988 designs, no four-digit
industries in SIC 20 were published separately. The addition of the eight industries in
1991 and its continuation in 1994 yielded greater reliability of the SIC 20 major group
estimates by having more sample cases in the publishable four-digit industries that
comprise SIC 20. Thus, overall reliability in SIC 20 was improved without adding sample
cases for that express purpose. |
Industries Where All Eligible Establishments Were Selected |
| Food industries include: |
| 2046 Wet Corn Milling |
| 2061 Cane Sugar, Except Refining |
| 2062 Cane Sugar Refining |
| 2063 Beet Sugar |
| 2075 Soybean Oil Mills |
| Paper industries include: |
| 2611 Pulp Mills |
| 2621 Paper Mills |
| 2631 Paperboard Mills |
| Chemical industries
include: |
| 2812 Alkalies and Chlorine |
| 2816 Inorganic Pigments |
| 2822 Synthetic Rubber |
| 2823 Cellulosic Manmade Fibers |
| 2824 Organic Fibers, Noncellulosic |
| 2861 Gum and Wood Chemicals |
| 2873 Nitrogenous Fertilizers |
| 2874 Phosphatic Fertilizers |
| 2895 Carbon Black |
| Petroleum industries includes: |
| 2911 Petroleum Refining. |
| Stone, Clay and Glass
industries include: |
| 3211 Flat Glass |
| 3221 Glass Containers |
| 3274 Lime |
| Primary Metal industries
include: |
| 3312 Blast Furnaces and Steel Mills |
| 3313 Electrometallurgical Products |
| 3331 Primary Copper |
| 3334 Primary Aluminum |
| 3339 Primary Nonferrous Metals, nec |
| 3353 Aluminum Sheet, Plate, and Foil |
| Remaining industries are represented by a survey sample of
eligible establishments. |
|
| Table B1. Sample Size by
Census Division, Industry Group and Selected Industry, 1994 |
SIC
Code |
Industry Group
and Industry |
Controlled Census Division |
No Controls |
Total |
|
New England |
Middle
Atlantic |
East North
Central |
West North
Central |
South
Atlantic |
East South
Central |
West South
Central |
Mountain |
Pacific |
|
| 2011 |
Meat
Packing Plants |
- |
- |
- |
37 |
- |
- |
- |
- |
- |
80 |
117 |
| 2033 |
Canned Fruits and Vegetables |
- |
- |
- |
- |
- |
- |
- |
- |
57 |
106 |
163 |
| 2037 |
Frozen
Fruits and Vegetables |
- |
- |
- |
- |
- |
- |
- |
- |
44 |
54 |
98 |
| 2046 |
Wet Corn Milling |
2 |
0 |
13 |
17 |
2 |
6 |
4 |
4 |
6 |
0 |
54 |
| 2051 |
Bread,
Cake, and Related Products |
- |
- |
- |
- |
- |
- |
- |
- |
- |
183 |
183 |
| 2061 |
Cane Sugar, Except Refining |
0 |
0 |
0 |
0 |
7 |
0 |
25 |
0 |
12 |
0 |
44 |
| 2062 |
Cane
Sugar Refining |
1 |
3 |
1 |
0 |
7 |
1 |
4 |
0 |
2 |
0 |
19 |
| 2063 |
Beet Sugar |
0 |
1 |
7 |
11 |
0 |
0 |
1 |
10 |
10 |
0 |
40 |
| 2075 |
Soybean
Oil Mills |
0 |
2 |
25 |
28 |
14 |
9 |
5 |
1 |
10 |
0 |
94 |
| 2082 |
Malt Beverages |
- |
- |
- |
- |
- |
- |
- |
- |
- |
30 |
30 |
| 20 |
Balance
of Food and Kindred Products |
113 |
184 |
218 |
188 |
204 |
146 |
172 |
109 |
216 |
0 |
1550 |
| 21 |
Tobacco Products |
- |
- |
- |
- |
18 |
- |
- |
- |
- |
17 |
35 |
| 22 |
Textile
Mill Products |
82 |
147 |
- |
- |
222 |
84 |
- |
- |
- |
101 |
636 |
| 23 |
Apparel and Other Textile Products
|
- |
271 |
- |
- |
204 |
171 |
- |
- |
268 |
198 |
1112 |
| 2421 |
Sawmills
and Planing Mills, General |
- |
- |
- |
- |
140 |
- |
- |
- |
121 |
213 |
474 |
| 2436 |
Softwood Veneer and Plywood |
- |
- |
- |
- |
- |
- |
- |
- |
- |
68 |
68 |
| 2493 |
Reconstituted
Wood Products |
- |
- |
- |
- |
- |
- |
- |
- |
- |
80 |
80 |
| 24 |
Balance of Lumber and Wood Products |
- |
- |
189 |
- |
222 |
- |
- |
- |
209 |
268 |
888 |
| 2511 |
Wood
Furniture, Except Upholstered |
- |
- |
- |
- |
- |
- |
- |
- |
- |
161 |
161 |
| 25 |
Furniture and Fixtures |
- |
- |
129 |
- |
- |
- |
- |
- |
- |
278 |
407 |
| 2611 |
Pulp
Mills |
1 |
3 |
12 |
1 |
11 |
9 |
0 |
0 |
10 |
0 |
47 |
| 2621 |
Paper Mills |
58 |
55 |
74 |
7 |
27 |
22 |
21 |
4 |
30 |
0 |
298 |
| 2631 |
Paperboard
Mills |
18 |
34 |
51 |
5 |
40 |
19 |
19 |
4 |
24 |
0 |
214 |
| 26 |
Balance of Paper and Allied
Products |
85 |
157 |
168 |
- |
142 |
- |
94 |
- |
124 |
132 |
902 |
| 27 |
Printing
and Publishing |
173 |
235 |
236 |
171 |
218 |
96 |
172 |
144 |
202 |
0 |
1647 |
| 2812 |
Alkalies and Chlorine |
3 |
4 |
3 |
3 |
8 |
3 |
11 |
3 |
6 |
0 |
44 |
| 2813 |
Industrial
Gases |
- |
22 |
33 |
- |
26 |
- |
27 |
- |
27 |
43 |
178 |
| 2816 |
Inorganic Pigments |
1 |
22 |
16 |
7 |
19 |
5 |
3 |
0 |
8 |
0 |
81 |
| 2819 |
Industrial
Inorganic Chemicals, nec. |
- |
- |
18 |
- |
28 |
19 |
29 |
11 |
33 |
63 |
201 |
| 2821 |
Plastics Materials and Resins |
- |
25 |
30 |
- |
30 |
20 |
33 |
- |
- |
40 |
178 |
| 2822 |
Synthetic
Rubber |
5 |
5 |
11 |
1 |
9 |
8 |
18 |
1 |
4 |
0 |
62 |
| 2823 |
Cellulosic Manmade Fibers |
0 |
1 |
0 |
0 |
2 |
5 |
1 |
0 |
0 |
0 |
9 |
| 2824 |
Organic
Fibers, Noncellulosic |
6 |
2 |
0 |
0 |
51 |
11 |
0 |
0 |
0 |
0 |
70 |
| 2861 |
Gum and Wood Chemicals |
3 |
4 |
3 |
13 |
9 |
5 |
16 |
1 |
2 |
0 |
56 |
| 2865 |
Cyclic
Crudes and Intermediates |
- |
- |
- |
- |
11 |
- |
13 |
- |
- |
44 |
68 |
| 2869 |
Industrial Organic Chemicals, nec.
|
- |
51 |
39 |
- |
39 |
17 |
46 |
- |
- |
57 |
249 |
| 2873 |
Nitrogenous
Fertilizers |
3 |
11 |
13 |
15 |
15 |
4 |
25 |
14 |
18 |
0 |
118 |
| 2874 |
Phosphatic Fertilizers |
0 |
4 |
5 |
7 |
33 |
4 |
7 |
6 |
1 |
0 |
67 |
| 287 |
Balance
of Agricultural Chemicals |
- |
- |
- |
- |
- |
- |
- |
- |
- |
40 |
40 |
| 2895 |
Carbon Black |
0 |
0 |
4 |
1 |
2 |
1 |
15 |
0 |
0 |
0 |
23 |
| 28 |
Balance
of Chemicals and Allied Products |
46 |
99 |
97 |
62 |
82 |
- |
- |
- |
82 |
91 |
559 |
| 2911 |
Petroleum Refining |
4 |
27 |
31 |
12 |
12 |
13 |
85 |
29 |
50 |
0 |
263 |
| 29 |
Balance
of Petroleum and Coal Products |
- |
110 |
99 |
- |
- |
- |
- |
- |
- |
187 |
396 |
| 3011 |
Tires and Inner Tubes |
- |
- |
- |
- |
- |
16 |
- |
- |
- |
30 |
46 |
| 308 |
Miscellaneous
Plastics Products, nec. |
118 |
211 |
235 |
113 |
162 |
123 |
125 |
80 |
193 |
0 |
1360 |
| 30 |
Balance of Rubber and Misc.
Products |
- |
- |
116 |
- |
77 |
- |
- |
- |
- |
168 |
361 |
| 31 |
Leather
and Leather Products |
- |
- |
- |
- |
- |
- |
- |
- |
- |
145 |
145 |
| 3211 |
Flat Glass |
2 |
9 |
9 |
1 |
8 |
7 |
7 |
2 |
9 |
0 |
54 |
| 3221 |
Glass
Containers |
3 |
17 |
15 |
2 |
16 |
0 |
10 |
1 |
14 |
0 |
78 |
| 3229 |
Pressed and Blown Glass, nec. |
- |
15 |
- |
- |
- |
- |
- |
- |
- |
33 |
48 |
| 3241 |
Cement,
Hydraulic |
- |
12 |
16 |
12 |
13 |
- |
16 |
- |
16 |
21 |
106 |
| 3274 |
Lime |
1 |
10 |
24 |
9 |
10 |
13 |
9 |
5 |
6 |
0 |
87 |
| 3296 |
Mineral
Wool |
- |
- |
- |
- |
- |
- |
- |
- |
- |
42 |
42 |
| 32 |
Balance of Stone, Clay, and Glass
Products |
- |
107 |
178 |
104 |
105 |
95 |
117 |
- |
156 |
215 |
1077 |
| 3312 |
Blast
Furnaces and Steel Mills |
4 |
75 |
81 |
11 |
31 |
29 |
27 |
5 |
25 |
0 |
288 |
| 3313 |
Electrometallurgical Products |
0 |
10 |
15 |
1 |
4 |
2 |
1 |
0 |
2 |
0 |
35 |
| 331 |
Balance
of Blast Furnace and Steel Products |
- |
- |
63 |
- |
- |
- |
- |
- |
- |
78 |
141 |
| 3321 |
Gray and Ductile Iron Foundries |
- |
- |
54 |
- |
- |
- |
- |
- |
- |
72 |
126 |
| 3331 |
Primary
Copper |
0 |
0 |
4 |
0 |
1 |
0 |
4 |
10 |
1 |
0 |
20 |
| 3334 |
Primary Aluminum |
3 |
2 |
5 |
1 |
7 |
5 |
3 |
2 |
15 |
0 |
43 |
| 3339 |
Primary
Nonferrous Metals, nec. |
5 |
24 |
14 |
5 |
4 |
8 |
5 |
8 |
15 |
0 |
88 |
| 3353 |
Aluminum Sheet, Plate, and Foil |
3 |
5 |
14 |
2 |
8 |
10 |
5 |
1 |
6 |
0 |
54 |
| 33 |
Primary
Metal Industries |
86 |
90 |
156 |
- |
49 |
72 |
70 |
- |
82 |
78 |
683 |
| 34 |
Fabricated Metal Products |
162 |
197 |
287 |
145 |
171 |
135 |
193 |
Overview of
Changes from Previous Surveys
MECS Home Page