Constructing special Consumer Price Indexes (CPIs) and their percent changes : U.S. Bureau of Labor Statistics

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Constructing special Consumer Price Indexes (CPIs) and their percent change

The Bureau of Labor Statistics (BLS) calculates many special aggregate indexes that are available in our online databases. Examples include all items less food and energy, all items less energy, and all items less food. This page shows how to calculate an aggregate series using data available on the CPI website.

When creating a special index, the weight of published indexes is a key component. To reflect the differences in the average expenditures on various items purchased, weights are assigned to each item. The cost weight of an item represents the expenditure, in dollars, on that item based on data collected as part of the Consumer Expenditure (CE) survey. Here, we use cost weights based on the U.S. all items cost weight rounded to the nearest hundred million dollars, and multiplied by the published relative importance values.

As a basic example, consider the expenditure class beverage materials including coffee and tea (SEFP), which is an aggregate of coffee (SEFP01) and other beverage materials including tea (SEFP02). In order to calculate the percent change in the aggregate series, we use the cost weight for the components in the weight update period (here we are using December 2022), as well as the index value for December 2022 and our period of interest, here January 2023.

First, we calculate the index relative for January 2023 for each component series. This is done by dividing the index value for the January 2023 by the index value for December 2022. Next, we update the cost weights for our component series using the index relative. To do this, we calculate the product of the cost weight for December 2022 and the index relative for January 2023, resulting in a new cost weight for January 2023.

The cost weight for an aggregate series is the sum of the cost weights for that aggregate’s component series. To find the cost weight for the beverage materials including coffee and tea aggregate, we sum the cost weights for coffee and other beverage materials including tea. Once this is done, we can calculate the percent change between these two cost weights to find the percent change in our aggregate series between December 2022 and January 2023.

This example is shown in table 1.

Table 1: Construction of beverage materials including coffee and tea (SEFP)
Item Code	Item Title	Cost Weight, December 2022	Index level, December 2022	Index level, January 2023	Index Relative, January 2023	Percent Change, January 2023	Cost Weight, January 2023	Percent Change in CW, January 2023
SEFP	Beverage materials including coffee and tea		139.208	141.512	1.017	1.7
SEFP01	Coffee	17367000000	234.473	239.827	1.023	2.3	17763561301
SEFP02	Other beverage materials including tea	9638685000	150.794	151.576	1.005	0.5	9688670090
	Total	27005685000					27452231391	1.7

Occasionally, a user wishes to estimate a price change that is not published by BLS. For instance, suppose a user would like a CPI series for ‘services less energy services and shelter’. This can be done by estimating a special index, in this case, ‘services less energy services and shelter’. It is important to remember that this estimate will not be an official CPI, though it can be used to estimate changes in prices for item categories not published by BLS.

This can be using the same methods as the beverage materials including coffee and tea example above, with an additional step. Since ‘services less energy services and shelter’ is not an officially published CPI item category, we first define it.

The CPI item aggregation page lists the definitions of published CPI item categories. In table 2, the definitions of services less energy services and shelter are given. Note that these differ slightly from those presented on the item aggregation page, because some of the series used as basic items in the estimation of published CPI series are not themselves published. Where this is the case, the expenditure class which contains those item categories is used instead. Once we have these definitions, we define ‘services less energy services and shelter’ as all of those items which are listed in the definition of services less energy services except for those which are also included in the definition of shelter. This definition is also shown in table 2.

Table 2: Composition of selected CPI aggregate items
Item	Item Title	Components
SASLE	Services less energy services	SEEB01, SEEB02, SEEB03, SEEB04, SEEB09, SEEC01, SEEC02, SEED03, SEED04, SEEE03, SEEE09, SEGC, SEGD01, SEGD02, SEGD03, SEGD04, SEGD05, SEGD09, SEHA01, SEHB01, SEHB02, SEHC01, SEHC09, SEHD01, SEHG01, SEHG02, SEHP01, SEHP02, SEHP03, SEHP04, SEHP09, SEMC01, SEMC02, SEMC03, SEMC04, SEMD01, SEMD02, SEMD03, SEME, SERA02, SERA04, SERB02, SERD02, SERD09, SERF01, SERF02, SERF03, SERF09, SETA03, SETA04, SETD01, SETD02, SETD03, SETD09, SETE, SETF01, SETF03, SETF09, SETG01, SETG02, SETG03, SETG09
SAH1	Shelter	SEHA01, SEHB01, SEHB02, SEHC01, SEHC09, SEHD01
n/a	'Services less energy services and shelter'	SEEB01, SEEB02, SEEB03, SEEB04, SEEB09, SEEC01, SEEC02, SEED03, SEED04, SEEE03, SEEE09, SEGC, SEGD01, SEGD02, SEGD03, SEGD04, SEGD05, SEGD09, SEHG01, SEHG02, SEHP01, SEHP02, SEHP03, SEHP04, SEHP09, SEMC01, SEMC02, SEMC03, SEMC04, SEMD01, SEMD02, SEMD03, SEME, SERA02, SERA04, SERB02, SERD02, SERD09, SERF01, SERF02, SERF03, SERF09, SETA03, SETA04, SETD01, SETD02, SETD03, SETD09, SETE, SETF01, SETF03, SETF09, SETG01, SETG02, SETG03, SETG09

Now following the same steps as in the simple beverage materials including coffee and tea example, we calculate ‘services less energy services and shelter’. This is shown in table 3.

Table 3: Construction of services less energy services and shelter
Item Code	Item Title	Cost Weight, December 2022	Index level, December 2022	Index level, January 2023	Index Relative, January 2023	Percent Change, January 2023	Cost Weight, January 2023	Percent Change in CW, January 2023
SEEB01	College tuition and fees	103941495000	916.495	916.002	0.999	-0.1	103885582903
SEEB02	Elementary and high school tuition and fees	26745180000	956.645	956.719	1.000	0.0	26747248838
SEEB03	Day care and preschool	49409115000	340.174	342.261	1.006	0.6	49712244642
SEEB04	Technical and business school tuition and fees	2257710000	268.689	269.401	1.003	0.3	2263692714
SEEB09	Unsampled tuition, other school fees, and childcare	6599460000			1.000	0.0	6599460000
SEEC01	Postage	5470605000	354.565	356.967	1.007	0.7	5507665604
SEEC02	Delivery services	868350000	392.261	416.625	1.062	6.2	922284700
SEED03	Wireless telephone services	125476575000	48.750	48.732	1.000	0.0	125430245188
SEED04	Residential telephone services	21014070000	145.719	148.163	1.017	1.7	21366518116
SEEE03	Internet services and electronic information providers	84229950000	81.332	82.159	1.010	1.0	85086416934
SEEE09	Unsampled information and information processing	607845000			1.000	0.0	607845000
SEGC	Personal care services	52708845000	322.018	322.717	1.002	0.2	52823259358
SEGD01	Legal services	20840400000	405.211	405.211	1.000	0.0	20840400000
SEGD02	Funeral expenses	14675115000	370.228	371.990	1.005	0.5	14744957239
SEGD03	Laundry and dry cleaning services	12330570000	211.187	212.302	1.005	0.5	12395671477
SEGD04	Apparel services other than laundry and dry cleaning	2344545000	248.369	250.111	1.007	0.7	2360989071
SEGD05	Financial services	15109290000	385.656	395.285	1.025	2.5	15486536441
SEGD09	Unsampled items	6599460000			1.000	0.0	6599460000
SEHG01	Water and sewerage maintenance	65734095000	639.319	646.581	1.011	1.1	66480766064
SEHG02	Garbage and trash collection	26050500000	565.185	570.412	1.009	0.9	26291422819
SEHP01	Domestic services	22837605000	205.307	206.259	1.005	0.5	22943502022
SEHP02	Gardening and lawncare services	27439860000	236.999		1.000	0.0	27439860000
SEHP03	Moving, storage, freight expense	9204510000	199.717	200.770	1.005	0.5	9253040416
SEHP04	Repair of household items	9725520000	325.578	319.469	0.981	-1.9	9543034692
SEHP09	Unsampled household operations	6512625000			1.000	0.0	6512625000
SEMC01	Physicians' services	161078925000	415.611	415.197	0.999	-0.1	160918470452
SEMC02	Dental services	79627695000	560.198	563.582	1.006	0.6	80108703715
SEMC03	Eyeglasses and eye care	27266190000	199.607	198.971	0.997	-0.3	27179312802
SEMC04	Services by other medical professionals	45501540000	255.471	255.438	1.000	0.0	45495662422
SEMD01	Hospital services	168459900000	383.150	385.064	1.005	0.5	169301430076
SEMD02	Nursing homes and adult day services	16151310000	263.996	269.002	1.019	1.9	16457577738
SEMD03	Care of invalids and elderly at home	12764745000	146.138	148.486	1.016	1.6	12969836224
SEME	Health insurance	66862950000	189.070	182.312	0.964	-3.6	64473042473
SERA02	Cable, satellite, and live streaming television service	75112275000	544.717	547.509	1.005	0.5	75497270276
SERA04	Purchase, subscription, and rental of video	10159695000	70.416	71.145	1.010	1.0	10264875891
SERB02	Pet services including veterinary	46543560000	306.453	310.869	1.014	1.4	47214254563
SERD02	Photographers and photo processing	3299730000	131.904	135.521	1.027	2.7	3390213408
SERD09	Unsampled photography	86835000			1.000	0.0	86835000
SERF01	Club membership for shopping clubs, fraternal, or other organizations, or participant sports fees	58787295000	155.473	156.205	1.005	0.5	59064078107
SERF02	Admissions	38033730000	428.825	433.278	1.010	1.0	38428679454
SERF03	Fees for lessons or instructions	15977640000	368.247	372.114	1.011	1.1	16145422857
SERF09	Unsampled recreation services	20493060000			1.000	0.0	20493060000
SETA03	Leased cars and trucks	63129045000	110.411	111.465	1.010	1.0	63731684351
SETA04	Car and truck rental	11028045000	184.218	175.721	0.954	-4.6	10519379732
SETD01	Motor vehicle body work	4949595000	399.411	401.172	1.004	0.4	4971417726
SETD02	Motor vehicle maintenance and servicing	50016960000	321.717	322.869	1.004	0.4	50196060072
SETD03	Motor vehicle repair	35949690000	234.246	240.662	1.027	2.7	36934352325
SETD09	Unsampled service policies	4949595000			1.000	0.0	4949595000
SETE	Motor vehicle insurance	218042685000	648.771	658.513	1.015	1.5	221316832330
SETF01	State motor vehicle registration and license fees	24140130000	190.938	192.801	1.010	1.0	24375667516
SETF03	Parking and other fees	17019660000	221.243	224.454	1.015	1.5	17266674045
SETF09	Unsampled motor vehicle fees	1823535000			1.000	0.0	1823535000
SETG01	Airline fares	50972145000	268.519	264.629	0.986	-1.4	50233718132
SETG02	Other intercity transportation	4254915000	163.190	161.377	0.989	-1.1	4207643961
SETG03	Intracity transportation	12591075000	340.709	336.875	0.989	-1.1	12449387573
SETG09	Unsampled public transportation	347340000			1.000	0.0	347340000
n/a	"Services less energy services and shelter"	2064154785000					2072656742460	0.4

Additional information

Additional information may be obtained from the Consumer Price Index Information Office by email or calling 202-691-7000. Information on the CPI's overall methodology can be found in the BLS Handbook of Methods.

Last Modified Date: October 23, 2023