Transmission of material in this release is embargoed until                                        
8:30 a.m. (EDT) October 10, 2019               USDL-19-1773

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

CONSUMER PRICE INDEX – SEPTEMBER 2019

The Consumer Price Index for All Urban Consumers (CPI-U) was unchanged in
September on a seasonally adjusted basis after rising 0.1 percent in August,
the U.S. Bureau of Labor Statistics reported today. Over the last 12 months,
the all items index increased 1.7 percent before seasonal adjustment.

Increases in the indexes for shelter and food were offset by declines in the
indexes for energy and used cars and trucks to result in the seasonally
adjusted all items index being flat. The energy index fell 1.4 percent as the
gasoline index declined 2.4 percent. The food index increased 0.1 percent in
September after being unchanged in each of the prior 3 months.   

The index for all items less food and energy rose 0.1 percent in September
after increasing 0.3 percent in each of the last 3 months. Along with the
shelter index, the indexes for medical care, household furnishings and
operations, and motor vehicle insurance all rose in September. The indexes for
used cars and trucks, apparel, new vehicles, and communication all declined.   

The all items index increased 1.7 percent for the 12 months ending September,
the same increase as for the 12 months ending August. The index for all items
less food and energy rose 2.4 percent over the last 12 months, also the same
increase as the period ending August. The food index increased 1.8 percent over
the last year, while the energy index decreased 4.8 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.
                              Mar.  Apr.  May   June  July  Aug.  Sep.   ended 
                              2019  2019  2019  2019  2019  2019  2019   Sep.  
                                                                         2019  
                                                                               
                                                                               
 All items..................    .4    .3    .1    .1    .3    .1    .0      1.7
  Food......................    .3   -.1    .3    .0    .0    .0    .1      1.8
   Food at home.............    .4   -.5    .3   -.2   -.1   -.2    .0       .6
   Food away from home (1)..    .2    .3    .2    .3    .2    .2    .3      3.2
  Energy....................   3.5   2.9   -.6  -2.3   1.3  -1.9  -1.4     -4.8
   Energy commodities.......   6.2   5.4   -.4  -3.5   2.4  -3.3  -2.3     -8.2
    Gasoline (all types)....   6.5   5.7   -.5  -3.6   2.5  -3.5  -2.4     -8.2
    Fuel oil................   2.1   1.3   -.3  -2.3    .6   -.9   -.8     -8.5
   Energy services..........    .3   -.1   -.8   -.7    .0   -.2   -.1      -.1
    Electricity.............    .4    .0   -.8   -.8    .6   -.3    .0       .7
    Utility (piped) gas                                                        
       service..............   -.1   -.8  -1.0   -.3  -1.8    .1   -.7     -2.7
  All items less food and                                                      
     energy.................    .1    .1    .1    .3    .3    .3    .1      2.4
   Commodities less food and                                                   
      energy commodities....   -.2   -.3   -.1    .4    .2    .2   -.3       .7
    New vehicles............    .4    .1    .1    .1   -.2   -.1   -.1       .1
    Used cars and trucks....   -.4  -1.3  -1.4   1.6    .9   1.1  -1.6      2.6
    Apparel.................  -1.9   -.8    .0   1.1    .4    .2   -.4      -.3
    Medical care commodities    .4    .9   -.4   -.2    .2    .3   -.6      -.3
   Services less energy                                                        
      services..............    .3    .3    .2    .3    .3    .3    .3      2.9
    Shelter.................    .4    .4    .2    .3    .3    .2    .3      3.5
    Transportation services     .0    .1    .1    .0    .3    .4    .3       .8
    Medical care services...    .3    .2    .5    .4    .5    .9    .4      4.4

   1 Not seasonally adjusted.

            
            
Food

The food index increased slightly in September, rising 0.1 percent. The index for
food at home was unchanged in September after falling in each of the prior 3 months.
Five of the six major grocery store food group indexes increased over the month. The
index for cereals and bakery products increased 0.5 percent after declining in August.
The indexes for meats, poultry, fish, and eggs and for other food at home both
increased 0.3 percent. The index for dairy and related products advanced 0.2 percent,
and the index for nonalcoholic beverages rose 0.1 percent.

These increases were offset by a decline in the index for fruits and vegetables, which
fell 1.0 percent in September following a 0.5-percent decline in August. The indexes
for fresh fruits and for fresh vegetables both declined in September. 

The index for food away from home rose 0.3 percent in September after increasing
0.2 percent in August. The index for full service meals increased 0.3 percent and the
index for limited service meals rose 0.2 percent.

The food at home index rose 0.6 percent over the last 12 months. Five of the six major
grocery store food group indexes rose over that span. The largest increase among them
was the 1.4-percent advance in the index for dairy and related products. The fruits
and vegetables index was the only one to decline, falling 0.4 percent. The index for
food away from home rose 3.2 percent over the last year. The index for full service
meals increased 3.6 percent and the index for limited service meals rose 3.0 percent.

Energy

The energy index declined 1.4 percent in September, its fourth decline in the last
5 months. The gasoline index fell 2.4 percent in September following a 3.5-percent
decline in August. (Before seasonal adjustment, gasoline prices fell 0.9 percent in
September.) The index for natural gas declined 0.7 percent in September, its eighth
decline in the last 9 months. The electricity index was unchanged in September
following a decline in August.  

The energy index decreased 4.8 percent over the past 12 months. The gasoline index
fell 8.2 percent, and the fuel oil index declined 8.5 percent over the year. The
index for natural gas declined 2.7 percent over the last 12 months. The index for
electricity was the only major energy component index to rise over the last year,
increasing 0.7 percent. 
 
All items less food and energy

The index for all items less food and energy increased 0.1 percent in September.
The shelter index continued to rise, increasing 0.3 percent in September following
a 0.2-percent increase in August. The index for rent rose 0.4 percent and the index
for owners’ equivalent rent increased 0.3 percent. The index for lodging away from
home increased 2.1 percent in September after falling 2.1 percent in August.  

The remaining indexes within all items less food and energy were a mix of offsetting
increases and declines. The medical care index rose 0.2 percent in September with its
component indexes mixed. The index for physicians’ services increased 0.4 percent,
the index for hospital services was unchanged, and the index for prescription drugs
declined 0.5 percent. The index for household furnishings and operations increased
0.3 percent over the month, as did the index for motor vehicle insurance. Also rising
in September were the indexes for airline fares, for tobacco, and for education.

The index for used cars and trucks declined in September, falling 1.6 percent. The
apparel index fell 0.4 percent in September after rising in each of the prior 3 months.
Also declining in September were the indexes for new vehicles, for communication, for
alcoholic beverages, and for personal care. The recreation index was unchanged in
September after rising in August.   

The index for all items less food and energy rose 2.4 percent over the past 12 months.
Indexes with larger increases included shelter and medical care (both 3.5 percent).
Indexes with smaller increases over the past 12 months included recreation
(1.0 percent)and new vehicles (0.1 percent). Indexes with declines over the past year
included communication (-1.2 percent) and apparel (-0.3 percent).   

Not seasonally adjusted CPI measures

The Consumer Price Index for All Urban Consumers (CPI-U) increased 1.7 percent over
the last 12 months to an index level of 256.759 (1982-84=100). For the month, the
index increased 0.1 percent prior to seasonal adjustment.  

The Consumer Price Index for Urban Wage Earners and Clerical Workers (CPI-W)
increased 1.5 percent over the last 12 months to an index level of 250.251
(1982-84=100). For the month, the index increased 0.1 percent prior to seasonal
adjustment.  

The Chained Consumer Price Index for All Urban Consumers (C-CPI-U) increased
1.6 percent over the last 12 months. For the month, the index increased 0.1 percent
on a not seasonally adjusted basis. Please note that the indexes for the past
10 to 12 months are subject to revision. 

_______________
The Consumer Price Index for October 2019 is scheduled to be released on Wednesday,
November 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 6,000 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. The factors are available at
www.bls.gov/cpi/tables/seasonal-adjustment/seasonal-factors-2019.pdf. 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 for January 2019, BLS adjusted 51 series using intervention
analysis seasonal adjustment, including selected food and beverage items, motor fuels, electricity,
and vehicles.

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. For January 2019, revised seasonal factors and seasonally adjusted
indexes for 2014 to 2018 were calculated and published. For series which are directly adjusted
using the Census X-13ARIMA-SEATS seasonal adjustment software, the seasonal factors for 2018 will
be applied to data for 2019 to produce the seasonally adjusted 2019 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 2019.

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
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.