Consumer Price Index Summary



Transmission of material in this release is embargoed until                                    
8:30 a.m. (EST) January 11, 2019               USDL-19-0018

Technical information: (202) 691-7000  •  cpi_info@bls.gov  •  www.bls.gov/cpi
Media Contact:         (202) 691-5902  •  PressOffice@bls.gov

CONSUMER PRICE INDEX –DECEMBER 2018

The Consumer Price Index for All Urban Consumers (CPI-U) declined 0.1 percent 
in December on a seasonally adjusted basis after being unchanged in November, 
the U.S. Bureau of Labor Statistics reported today. Over the last 12 months, 
the all items index increased 1.9 percent before seasonal adjustment.

The seasonally adjusted decline in the all items index was caused by a sharp
decrease in the gasoline index, which fell 7.5 percent in December. This
decline more than offset increases in several indexes including shelter, food,
and other energy components. The energy index fell 3.5 percent, as the gasoline
and fuel oil indexes fell, but the indexes for natural gas and for electricity
increased. The food index increased 0.4 percent in December.

The index for all items less food and energy increased 0.2 percent in December,
the same increase as in October and November. Along with the index for shelter,
the indexes for recreation, medical care, and household furnishings and
operations all increased in December, while the indexes for airline fares, used
cars and trucks, and motor vehicle insurance all declined. 

The all items index increased 1.9 percent for the 12 months ending December;
this was the first time the 12-month change has been under 2.0 percent since
August 2017. The index for all items less food and energy rose 2.2 percent over
the last 12 months, the same increase as for the 12 months ending November. The
food index rose 1.6 percent over the past year, while the energy index declined
0.3 percent. 

 Table A. Percent changes in CPI for All Urban Consumers (CPI-U): U.S. city
 average
                                                                               
                                                                               
                                  Seasonally adjusted changes from             
                                          preceding month                      
                                                                          Un-  
                                                                       adjusted
                                                                        12-mos.
                              June  July  Aug.  Sep.  Oct.  Nov.  Dec.   ended 
                              2018  2018  2018  2018  2018  2018  2018   Dec.  
                                                                         2018  
                                                                               
                                                                               
 All items..................    .1    .2    .2    .1    .3    .0   -.1      1.9
  Food......................    .2    .1    .1    .0   -.1    .2    .4      1.6
   Food at home.............    .2    .2    .0   -.1   -.2    .2    .3       .6
   Food away from home (1)..    .2    .1    .2    .2    .1    .3    .4      2.8
  Energy....................   -.3   -.5   1.9   -.5   2.4  -2.2  -3.5      -.3
   Energy commodities.......    .6   -.6   3.0   -.2   2.9  -4.1  -7.4     -1.8
    Gasoline (all types)....    .5   -.6   3.0   -.2   3.0  -4.2  -7.5     -2.1
    Fuel oil................   2.9   1.2   2.2    .3   3.7  -2.9 -11.4      1.9
   Energy services..........  -1.5   -.4    .4   -.8   1.7    .4   1.8      1.4
    Electricity.............  -1.4   -.4    .3   -.5   2.3    .3    .7      1.1
    Utility (piped) gas                                                        
       service..............  -1.7   -.5    .9  -1.7   -.6    .7   5.6      2.3
  All items less food and                                                      
     energy.................    .2    .2    .1    .1    .2    .2    .2      2.2
   Commodities less food and                                                   
      energy commodities....    .0    .1   -.3   -.3    .3    .2    .1       .1
    New vehicles............    .4    .3    .0   -.1   -.2    .0    .0      -.3
    Used cars and trucks....    .7   1.3    .4  -3.0   2.6   2.4   -.2      1.4
    Apparel.................   -.9   -.3  -1.6    .9    .1   -.9    .0      -.1
    Medical care commodities    .2  -1.1   -.3   -.1   -.1    .4   -.2      -.5
   Services less energy                                                        
      services..............    .2    .3    .2    .2    .2    .2    .3      2.9
    Shelter.................    .1    .3    .3    .2    .2    .3    .3      3.2
    Transportation services     .2    .5    .3    .5    .1   -.3   -.2      2.8
    Medical care services...    .5    .1   -.2    .2    .2    .4    .4      2.6

   1 Not seasonally adjusted.  


Food

The food index rose 0.4 percent in December, the largest increase since May
2014. The food at home index rose 0.3 percent, as the index for fruits and
vegetables increased 1.7 percent. The index for fresh fruits rose 1.3 percent
and the fresh vegetables index increased 2.6 percent.  

The index for cereals and bakery products advanced 0.4 percent, and the indexes
for dairy and related products and for nonalcoholic beverages both increased
0.3 percent. The index for meats, poultry, fish, and eggs was unchanged, while
the only major grocery store food group index to decline was other food at home,
which fell 0.3 percent. The index for food away from home rose 0.4 percent,
with the indexes for both full service meals and limited service meals
increasing.

The index for food at home rose 0.6 percent over the past year, with four of the
six major grocery store food groups increasing over the span. The food away
from home index increased 2.8 percent over the past 12 months. 

Energy

The energy index fell 3.5 percent in December following a 2.2-percent decline
in November. The gasoline index fell 7.5 percent in December after a 4.2-percent
decline the prior month. (Before seasonal adjustment, gasoline prices fell 9.9
percent in December.) The fuel oil index also declined sharply in December,
falling 11.4 percent. However, the other major energy component indexes rose
in December, with the index for natural gas increasing 5.6 percent and the
electricity index rising 0.7 percent.

The energy index fell 0.3 percent over the past 12 months; this represented the
first 12-month decline in the energy index since the period ending September
2016. The gasoline index declined 2.1 percent over the last year, more than
offsetting increases in the other component indexes. The electricity index rose
1.1 percent, the index for natural gas increased 2.3 percent, and the fuel oil
index advanced 1.9 percent. 
  
 
All items less food and energy

The index for all items less food and energy increased 0.2 percent in December.
The shelter index increased 0.3 percent in December, the same increase as the
prior month. The indexes for rent and owners' equivalent rent both increased 0.2
percent, while the index for lodging away from home rose 2.7 percent. 

The recreation index rose in December, increasing 0.6 percent. The medical care
index rose 0.3 percent in December with its major component indexes mixed. The
index for hospital services rose 0.5 percent, the physicians' services index was
unchanged, and the index for prescription drugs declined 0.4 percent. The index
for household furnishings and operations rose 0.3 percent in December, and the
education index rose 0.2 percent.

The index for airline fares fell 1.5 percent in December following a 2.4-percent
decline in November. The index for used cars and trucks fell 0.2 percent after
rising in October and November. The motor vehicle insurance index fell 0.2
percent, its second consecutive decline. Several indexes were unchanged in
December, including those for new vehicles, apparel, and communication.      

The index for all items less food and energy rose 2.2 percent over the past 12
months, the same increase for the period ending November. The shelter index
increased 3.2 percent over the last year, and the medical care index rose 2.0
percent.  

Not seasonally adjusted CPI measures

The Consumer Price Index for All Urban Consumers (CPI-U) increased 1.9 percent
over the last 12 months to an index level of 251.233 (1982-84=100). For the
month, the index decreased 0.3 percent prior to seasonal adjustment.  

The Consumer Price Index for Urban Wage Earners and Clerical Workers (CPI-W)
increased 1.8 percent over the last 12 months to an index level of 244.786
(1982-84=100). For the month, the index decreased 0.5 percent prior to seasonal
adjustment.  

The Chained Consumer Price Index for All Urban Consumers (C-CPI-U) increased
1.8 percent over the last 12 months. For the month, the index declined 0.3
percent on a not seasonally adjusted basis. Please note that the indexes for
the past 10 to 12 months are subject to revision. 

Year in Review (December to December)

The all items CPI rose 1.9 percent in 2018, a smaller increase than the 2.1
percent increase in 2016 and 2017, but larger than the increases in any of the
years from 2012 to 2015. It was also slightly larger than the 1.8-percent
average annual increase over the past 10 years. 

The food index increased 1.6 percent in 2018, the same increase as in 2017. The
index for food at home increased 0.6 percent in 2018 following a 0.9-percent
increase in 2017.   

Four of the six major grocery store food group indexes increased in 2018. The
index for cereals and bakery products increased the most, rising 1.7 percent
after declining in 2016 and 2017. The fruits and vegetables index, which rose
1.5 percent in 2017, increased 1.6 percent in 2018. The index for nonalcoholic
beverages increased 1.4 percent in 2018 after being unchanged in 2017. The
index for other food at home also increased in 2018, rising 0.2 percent after
advancing 0.5 percent the prior year.  

In contrast, the index for meats, poultry, fish, and eggs declined in 2018,
falling 0.4 percent after rising 2.8 percent in 2017. The dairy and related
products index fell slightly in 2018, decreasing 0.1 percent, the fourth yearly
decline in a row.  

The index for food away from home rose 2.8 percent in 2018 after a 2.5-percent
increase the prior year. Over the last 10 years, the food index rose at an
average annual rate of 1.6 percent. The food at home index rose at a 0.9-percent
rate, and the index for food away from home increased at a 2.4-percent rate
since December 2008. 

The energy index fell slightly in 2018, declining 0.3 percent after rising 6.9
percent in 2017. The gasoline index fell 2.1 percent in 2018 after rising in
2016 and 2017. The decline in the gasoline index more than offset increases in
other energy component indexes. The index for electricity increased 1.1 percent
in 2018 after rising 2.6 percent the prior year. The index for natural gas rose
for the third consecutive year, increasing 2.3 percent. The fuel oil index rose
1.9 percent in 2018. The energy index increased at a 1.9-percent average annual
rate over the past 10 years.    

The index for all items less food and energy rose 2.2 percent in 2018, a larger
increase than its 1.8-percent rise in 2017 and 1.8-percent average annual
increase over the past 10 years. The shelter index rose 3.2 percent in 2018,
the same increase as in 2017. The rent index rose 3.5 percent in 2018, while
the index for owners' equivalent rent increased 3.2 percent. The index for
household furnishings and operations increased 2.1 percent after falling in
each of the prior 5 years.  

The medical care index rose 2.0 percent in 2018, a slightly larger increase
than its 1.8-percent increase the prior year. The index for hospital services
rose 3.7 percent, while the physicians' services index increased 0.6 percent.
The index for prescription drugs, however, fell 0.6 percent in 2018. 

The index for motor vehicle insurance rose 4.6 percent in 2018 following larger
increases in recent years. The index for new vehicles fell for the second year
in a row, decreasing 0.3 percent after a 0.5-percent decline in 2017. The index
for used cars and trucks rose 1.4 percent in 2018 after decreasing in each of
the prior 2 years. 
 
The education index increased 2.6 percent in 2018 after a 2.0-percent rise in
2017. The index for communication declined 1.8 percent in 2018, its ninth
consecutive yearly decline. The recreation index rose 1.2 percent, and the
index for personal care increased 1.8 percent. The index for tobacco increased
3.4 percent, and the alcoholic beverages index rose 1.8 percent. 

The index for airline fares decreased for the sixth year in a row in 2018,
falling 2.6 percent. The apparel index declined for the fifth consecutive year,
though it decreased only 0.1 percent in 2018. 


	

The Consumer Price Index for January 2019 is scheduled to be released on Wednesday, February 13, 2019, at 8:30 a.m. (EST). 


Technical Note 

Brief Explanation of the CPI

The Consumer Price Index (CPI) measures the change in prices paid by consumers
for goods and services. The CPI reflects spending patterns for each of two
population groups: all urban consumers and urban wage earners and clerical
workers. The all urban consumer group represents about 93 percent of the total
U.S. population. It is based on the expenditures of almost all residents of
urban or metropolitan areas, including professionals, the self-employed, the
poor, the unemployed, and retired people, as well as urban wage earners and
clerical workers. Not included in the CPI are the spending patterns of people
living in rural nonmetropolitan areas, farming families, people in the Armed
Forces, and those in institutions, such as prisons and mental hospitals.
Consumer inflation for all urban consumers is measured by two indexes, namely,
the Consumer Price Index for All Urban Consumers (CPI-U) and the Chained
Consumer Price Index for All Urban Consumers (C-CPI-U).

The Consumer Price Index for Urban Wage Earners and Clerical Workers (CPI-W)
is based on the expenditures of households included in the CPI-U definition
that meet two requirements: more than one-half of the household's income must
come from clerical or wage occupations, and at least one of the household's
earners must have been employed for at least 37 weeks during the previous
12 months. The CPI-W population represents about 29 percent of the total U.S.
population and is a subset of the CPI-U population.

The CPIs are based on prices of food, clothing, shelter, fuels, transportation,
doctors’ and dentists’ services, drugs, and other goods and services that
people buy for day-to-day living. Prices are collected each month in 75 urban
areas across the country from about 5,000 housing units and approximately
22,000 retail establishments (department stores, supermarkets, hospitals,
filling stations, and other types of stores and service establishments).  All
taxes directly associated with the purchase and use of items are included in
the index. Prices of fuels and a few other items are obtained every month in
all 75 locations. Prices of most other commodities and services are collected
every month in the three largest geographic areas and every other month in
other areas. Prices of most goods and services are obtained by personal visits
or telephone calls by the Bureau’s trained representatives.

In calculating the index, price changes for the various items in each location
are aggregated using weights, which represent their importance in the spending
of the appropriate population group. Local data are then combined to obtain a
U.S. city average. For the CPI-U and CPI-W, separate indexes are also published
by size of city, by region of the country, for cross-classifications of regions
and population-size classes, and for 23 selected local areas. Area indexes do
not measure differences in the level of prices among cities; they only measure
the average change in prices for each area since the base period. For the
C-CPI-U, data are issued only at the national level. The CPI-U and CPI-W are
considered final when released, but the C-CPI-U is issued in preliminary form
and subject to three subsequent quarterly revisions.

The index measures price change from a designed reference date. For most of the
CPI-U and the CPI-W, the reference base is 1982-84 equals 100. The reference
base for the C-CPI-U is December 1999 equals 100.  An increase of 7 percent from
the reference base, for example, is shown as 107.000. Alternatively, that
relationship can also be expressed as the price of a base period market basket
of goods and services rising from $100 to $107.

Sampling Error in the CPI

The CPI is a statistical estimate that is subject to sampling error because it
is based upon a sample of retail prices and not the complete universe of all
prices. BLS calculates and publishes estimates of the 1-month, 2-month, 6-month,
and 12-month percent change standard errors annually for the CPI-U. These
standard error estimates can be used to construct confidence intervals for
hypothesis testing. For example, the estimated standard error of the 1-month
percent change is 0.03 percent for the U.S. all items CPI. This means that if
we repeatedly sample from the universe of all retail prices using the same
methodology, and estimate a percentage change for each sample, then 95 percent
of these estimates will be within 0.06 percent of the 1-month percentage
change based on all retail prices. For example, for a 1-month change of
0.2 percent in the all items CPI-U, we are 95 percent confident that the actual
percent change based on all retail prices would fall between 0.14 and
0.26 percent. For the latest data, including information on how to use the
estimates of standard error,
see https://www.bls.gov/cpi/tables/variance-estimates/home.htm.

Calculating Index Changes

Movements of the indexes from 1 month to another are usually expressed as percent changes
rather than changes in index points, because index point changes are affected by the level
of the index in relation to its base period, while percent changes are not. The following
table shows an example of using index values to calculate percent changes:
 
                                 Item A                   Item B                    Item C
Year I                          112.500                  225.000                   110.000
Year II                         121.500                  243.000                   128.000
Change in index points            9.000                   18.000                    18.000
Percent change 9.0/112.500 x 100 = 8.0  18.0/225.000 x 100 = 8.0 18.0/110.000 x 100 = 16.4

Use of Seasonally Adjusted and Unadjusted Data

The Consumer Price Index (CPI) produces both unadjusted and seasonally adjusted data.
Seasonally adjusted data are computed using seasonal factors derived by the X-13ARIMA-SEATS
seasonal adjustment method. These factors are updated each February, and the new factors are
used to revise the previous 5 years of seasonally adjusted data. For more information on data
revision scheduling, please see the Factsheet on Seasonal Adjustment
at www.bls.gov/cpi/seasonal-adjustment/questions-and-answers.htm
and the Timeline of Seasonal Adjustment Methodological Changes
at www.bls.gov/cpi/seasonal-adjustment/timeline-seasonal-adjustment-methodology-changes.htm.

For analyzing short-term price trends in the economy, seasonally adjusted changes are usually
preferred since they eliminate the effect of changes that normally occur at the same time and
in about the same magnitude every year—such as price movements resulting from weather events,
production cycles, model changeovers, holidays, and sales. This allows data users to focus on
changes that are not typical for the time of year. The unadjusted data are of primary interest
to consumers concerned about the prices they actually pay. Unadjusted data are also used
extensively for escalation purposes. Many collective bargaining contract agreements and pension
plans, for example, tie compensation changes to the Consumer Price Index before adjustment for
seasonal variation. BLS advises against the use of seasonally adjusted data in escalation
agreements because seasonally adjusted series are revised annually.

Intervention Analysis

The Bureau of Labor Statistics uses intervention analysis seasonal adjustment for some CPI series.
Sometimes extreme values or sharp movements can distort the underlying seasonal pattern of price
change. Intervention analysis seasonal adjustment is a process by which the distortions caused by
such unusual events are estimated and removed from the data prior to calculation of seasonal
factors. The resulting seasonal factors, which more accurately represent the seasonal pattern, are
then applied to the unadjusted data.

For example, this procedure was used for the motor fuel series to offset the effects of the 2009
return to normal pricing after the worldwide economic downturn in 2008. Retaining this outlier
data during seasonal factor calculation would distort the computation of the seasonal portion of
the time series data for motor fuel, so it was estimated and removed from the data prior to
seasonal adjustment. Following that, seasonal factors were calculated based on this “prior adjusted”
data. These seasonal factors represent a clearer picture of the seasonal pattern in the data. The
last step is for motor fuel seasonal factors to be applied to the unadjusted data.

For the seasonal factors introduced in January 2018, BLS adjusted 38 series using intervention
analysis seasonal adjustment, including selected food and beverage items, motor fuels, and
natural gas.

Revision of Seasonally Adjusted Indexes

Seasonally adjusted data, including the U.S. city average all items index levels, are subject to
revision for up to 5 years after their original release. Every year, economists in the CPI
calculate new seasonal factors for seasonally adjusted series and apply them to the last 5 years
of data. Seasonally adjusted indexes beyond the last 5 years of data are considered to be final
and not subject to revision. In January 2018, revised seasonal factors and seasonally adjusted
indexes for 2013 to 2017 were calculated and published. For series which are directly adjusted
using the Census X-13ARIMA-SEATS seasonal adjustment software, the seasonal factors for 2017
will be applied to data for 2018 to produce the seasonally adjusted 2018 indexes. Series which
are indirectly seasonally adjusted by summing seasonally adjusted component series have seasonal
factors which are derived and are therefore not available in advance.

Determining Seasonal Status

Each year the seasonal status of every series is reevaluated based upon certain statistical
criteria. Using these criteria, BLS economists determine whether a series should change its
status from "not seasonally adjusted" to "seasonally adjusted", or vice versa. If any of the
81 components of the U.S. city average all items index change their seasonal adjustment status
from seasonally adjusted to not seasonally adjusted, not seasonally adjusted data will be used
in the aggregation of the dependent series for the last 5 years, but the seasonally adjusted
indexes before that period will not be changed. Twenty-nine of the 81 components of the
U.S. city average all items index are not seasonally adjusted for 2018.

Contact Information

For additional information about the CPI visit www.bls.gov/cpi or contact the CPI Information
and Analysis Section at 202-691-7000 or cpi_info@bls.gov.

For additional information on seasonal adjustment in the CPI visit
https://www.bls.gov/cpi/seasonal-adjustment/home.htm or contact the CPI seasonal adjustment
section at 202-691-6968 or cpiseas@bls.gov.

Information from this release will be made available to sensory impaired individuals upon request.
Voice phone: 202-691-5200; Federal Relay Service: 1-800-877-8339.

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Last Modified Date: January 11, 2019