Impact of the coronavirus (COVID-19) pandemic on Consumer Price Index data for September 2021

Note: Table 1 has been updated to correct values for August 2021 on telephone and online collection for the commodities and services survey.

This page provides further information on the effects of the COVID-19 pandemic for the September 2021 Consumer Price Index news release.

Collection mode

Data collection for September 2021 involved no personal visits, so all data were collected either online or through telephone interviews. An example of this is full-service restaurants; even if a restaurant was open for dine-in service, as well as open for take-out or delivery, the data collector attempted to obtain the price from the restaurant’s website or by telephone call with the respondent, rather than a personal visit.

Table 1. Collection modes for the commodities and services price survey, percent
Month	2019			2020			2021
Month	Personal visit	Telephone	Online	Personal visit	Telephone	Online	Personal visit	Telephone	Online
January	73	10	17	72	9	19	0	16	84
February	72	11	17	72	10	18	0	16	84
March	74	10	16	44	14	42	0	16	84
April	74	10	16	0	18	82	0	16	84
May	74	10	16	0	17	83	0	15	85
June	73	10	17	0	17	83	0	15	85
July	74	10	16	0	17	83	0	15	85
August	73	10	17	0	17	83	0	15	85
September	73	10	17	0	17	83	0	15	85
October	73	10	17	0	16	84
November	73	9	18	0	16	84
December	72	10	18	0	16	84
Average, Feb 2019–Feb 2020	73	10	17

Table 2. Collection modes for the housing survey, percent
Month	2019		2020		2021
Month	Personal visit	Telephone	Personal visit	Telephone	Personal visit	Telephone
January	35	65	39	61	0	100
February	36	64	40	60	0	100
March	36	64	30	70	0	100
April	38	62	0	100	0	100
May	39	61	0	100	0	100
June	38	62	0	100	0	100
July	37	63	0	100	0	100
August	37	63	0	100	0	100
September	38	62	0	100	0	100
October	39	61	0	100
November	38	62	0	100
December	39	61	0	100
Average, Feb 2019–Feb 2020	38	62

Response rates

For some CPI market basket categories, the percentage of the sample collected in September 2021 was notably lower than the average before the pandemic. These included leased cars and trucks, food from vending machines and mobile vendors, new vehicles, and fuel oil. There was a lower percentage of collected rents in September 2021 compared with September 2020.

Table 3. Response rates for the commodities and services price survey, percent
Month	2019		2020		2021
Month	Collected prices	Uncollected prices	Collected prices	Uncollected prices	Collected prices	Uncollected prices
January	85	15	86	14	77	23
February	85	15	87	13	79	21
March	87	13	76	25	78	22
April	86	14	65	35	78	22
May	87	13	68	32	78	22
June	86	14	70	30	78	22
July	86	14	70	30	78	22
August	86	14	72	28	79	21
September	86	14	73	27	80	20
October	86	14	74	26
November	87	13	75	25
December	86	14	77	23
Average, Feb 2019–Feb 2020	86	14

Table 4. Response rates for the housing survey, percent
Month	2019			2020			2021
Month	Collected rents	Vacant units	Uncollected rents	Collected rents	Vacant units	Uncollected rents	Collected rents	Vacant units	Uncollected rents
January	68	6	26	70	5	25	58	4	38
February	67	5	28	69	6	25	61	4	35
March	67	6	27	63	5	32	62	4	34
April	68	6	26	61	4	35	62	3	35
May	69	6	25	61	4	35	63	3	34
June	68	6	26	62	4	34	62	4	34
July	69	6	25	60	4	36	55	3	42
August	67	6	27	62	4	34	58	3	39
September	65	6	29	60	4	36	59	3	38
October	69	5	26	59	4	37
November	69	6	25	60	4	36
December	67	6	27	62	4	34
Average, Feb 2019–Feb 2020	68	6	26

Imputation

In September 2021, the CPI continued to impute the majority of uncollected prices from collected prices within the same item and geographic area (home cell). There were no instances where the data from the previous month were imputed to the current month (carry forward).

Table 5. Imputation source for the commodities and services price survey, percent
Month	2019			2020			2021
Month	Home cell	Different cell	Carry forward	Home cell	Different cell	Carry forward	Home cell	Different cell	Carry forward
January	93	7	0	92	8	0	89	11	0
February	91	9	0	93	7	0	88	12	0
March	94	6	0	90	10	0	88	12	0
April	92	8	0	84	16	0	88	12	0
May	92	8	0	85	15	0	87	13	0
June	92	8	0	86	14	0	87	13	0
July	92	8	0	86	14	0	87	13	0
August	91	9	0	86	14	0	88	12	0
September	93	7	0	87	13	0	88	12	0
October	91	9	0	88	12	0
November	93	7	0	89	11	0
December	92	8	0	88	12	0

Nonvacant units with respondents previously reporting, but not currently reporting, receive noninterview imputation for use in the CPI. Vacant units that were previously occupied by renters are also imputed for use in estimation by separate methods. Table 6 below shows a reduction in vacancy imputation performed in the current month relative to the same time in 2019.

Table 6. Imputation source for the housing survey, percent
Month	2019		2020		2021
Month	Noninterview	Vacancy	Noninterview	Vacancy	Noninterview	Vacancy
January	81	19	82	18	91	9
February	84	16	81	19	89	11
March	82	18	87	13	89	11
April	82	18	90	10	92	8
May	82	18	91	9	91	9
June	81	19	89	11	90	10
July	81	19	89	11	93	7
August	83	17	91	9	93	7
September	83	17	90	10	92	8
October	83	17	90	10
November	82	18	90	10
December	82	18	90	10

Cell, series, index, or observation suppression

Table 7 lists the data series that were both inadequate for publication in September 2021 because of insufficient sample and that were adequate over the year before March 2020.

Table 7. List of data inadequate for publication for September 2021
LABSTAT ID	Item	Area
CPI-U Series
CUUR0000SETA03	Leased cars and trucks	U.S. city average
CUURS35DSAGS	Other personal services	Tampa-St. Petersburg-Clearwater, FL
CUURS48BSAM	Medical care	Denver-Aurora-Lakewood, CO
CUURS48BSATCLTB	Transportation commodities less motor fuel	Denver-Aurora-Lakewood, CO
CUURS48BSETA	New and used motor vehicles	Denver-Aurora-Lakewood, CO
CUURS48BSETA01	New vehicles	Denver-Aurora-Lakewood, CO
CUURS49FSAGS	Other personal services	Urban Hawaii
CPI-W Series
CWUR0000SETA03	Leased cars and trucks	U.S. city average
CWURS11ASAGC	Other goods	Boston-Cambridge-Newton, MA-NH
CWURS35DSAGS	Other personal services	Tampa-St. Petersburg-Clearwater, FL
CWURS48BSAM	Medical care	Denver-Aurora-Lakewood, CO
CWURS48BSETA	New and used motor vehicles	Denver-Aurora-Lakewood, CO
CWURS48BSETA01	New vehicles	Denver-Aurora-Lakewood, CO
CWURS49FSAGS	Other personal services	Urban Hawaii
C-CPI-U Series
No series were inadequate for publication.
AP Series
APU0000706311	Turkey, frozen, whole, per lb. (453.6 gm)	U.S. city average
APU0000711311	Oranges, Navel, per lb. (453.6 gm)	U.S. city average
APU0000711411	Grapefruit, per lb. (453.6 gm)	U.S. city average
APU0000711412	Lemons, per lb. (453.6 gm)	U.S. city average
APU0000712211	Lettuce, iceberg, per lb. (453.6 gm)	U.S. city average
APU0000712406	Peppers, sweet, per lb. (453.6 gm)	U.S. city average
APU0000712412	Broccoli, per lb. (453.6 gm)	U.S. city average
APU0000FL2101	Lettuce, romaine, per lb. (453.6 gm)	U.S. city average
APU0100711211	Bananas, per lb. (453.6 gm)	Northeast urban
APU0100711311	Oranges, Navel, per lb. (453.6 gm)	Northeast urban
APU0100711411	Grapefruit, per lb. (453.6 gm)	Northeast urban
APU0100711412	Lemons, per lb. (453.6 gm)	Northeast urban
APU0100711415	Strawberries, dry pint, per 12 oz. (340.2 gm)	Northeast urban
APU0200702212	Bread, whole wheat, pan, per lb. (453.6 gm)	Midwest urban
APU0200709112	Milk, fresh, whole, fortified, per gal. (3.8 lit)	Midwest urban
APU0200710411	Ice cream, prepackaged, bulk, regular, per 1/2 gal. (1.9 lit)	Midwest urban
APU0200711411	Grapefruit, per lb. (453.6 gm)	Midwest urban
APU0200711412	Lemons, per lb. (453.6 gm)	Midwest urban
APU0300702212	Bread, whole wheat, pan, per lb. (453.6 gm)	South urban
APU0300702421	Cookies, chocolate chip, per lb. (453.6 gm)	South urban
APU0300705121	Bologna, all beef or mixed, per lb. (453.6 gm)	South urban
APU0300710411	Ice cream, prepackaged, bulk, regular, per 1/2 gal. (1.9 lit)	South urban
APU0300711311	Oranges, Navel, per lb. (453.6 gm)	South urban
APU0300711411	Grapefruit, per lb. (453.6 gm)	South urban
APU0300711412	Lemons, per lb. (453.6 gm)	South urban
APU0300711417	Grapes, Thompson Seedless, per lb. (453.6 gm)	South urban
APU0300712211	Lettuce, iceberg, per lb. (453.6 gm)	South urban
APU0300716116	Margarine, soft, tubs, per lb. (453.6 gm)	South urban
APU0300FL2101	Lettuce, romaine, per lb. (453.6 gm)	South urban
APU0400702212	Bread, whole wheat, pan, per lb. (453.6 gm)	West urban
APU0400705111	Frankfurters, all meat or all beef, per lb. (453.6 gm)	West urban
APU0400711411	Grapefruit, per lb. (453.6 gm)	West urban
APU0400711415	Strawberries, dry pint, per 12 oz. (340.2 gm)	West urban
APU0400714233	Beans, dried, any type, all sizes, per lb. (453.6 gm)	West urban
APU0400FL2101	Lettuce, romaine, per lb. (453.6 gm)	West urban

Measures of error

The standard error of the CPI’s change can be used to construct confidence intervals to determine whether the change for a particular CPI series is significantly different from zero. Table 8 shows the 1- and 12-month standard error for selected indexes at the U.S. level.

Table 8. Impact on standard errors of one- and twelve-month percent changes
Item	One month			Twelve month
Item	Sep 2019	Sep 2020	Sep 2021	Sep 2019	Sep 2020	Sep 2021
All items	0.04	0.03	0.04	0.09	0.09	0.08
Food and beverages	0.07	0.08	0.08	0.21	0.14	0.19
Food	0.08	0.08	0.09	0.23	0.16	0.19
Housing	0.06	0.04	0.06	0.13	0.14	0.13
Apparel	0.54	0.50	0.44	0.81	0.80	0.85
Transportation	0.10	0.13	0.07	0.16	0.26	0.29
Medical care	0.20	0.10	0.13	0.45	0.46	0.30
Recreation	0.16	0.17	0.16	0.38	0.37	0.40
Education and communication	0.11	0.12	0.09	0.21	0.21	0.23
Other goods and services	0.10	0.12	0.15	0.26	0.29	0.38
Energy	0.16	0.09	0.07	0.28	0.28	0.40
All items less food and energy	0.04	0.04	0.05	0.09	0.11	0.10

Last Modified Date: November 22, 2021