Quality Adjustment in the CPI: Women’s Outerwear : U.S. Bureau of Labor Statistics

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Bureau of Labor Statistics > Consumer Price Index > Methods > Quality Adjustment

Quality Adjustment in the CPI: Women’s Outerwear

Item definition

The Entry Level Item (ELI) category of Women’s Outerwear is part of the index for Women’s Apparel. Here, we examine the hedonic regression model used in the quality adjustment of price data for those items.

CPI sample

The sample used for the current hedonic model for women’s outerwear included 1,112 observations from an extract of CPI data for the months of April and May 2024. There were more than 350 unique brands in the sample, with most brands having fewer than 20 observations. Additionally, the sample included just shy of 100 outlets of both the brick and e-commerce variety; the top outlet was about 10 percent of the sample.

Current Model

Table 1 presents the details of the estimation of the current model used to quality adjust women’s outerwear.

Table 1. Parameter estimates for the hedonic regression for women's outerwear
Variable	Parameter Estimate	Standard Error	T Value	Pr > \| t \|	Tolerance Statistic
Intercept	4.556	0.046	99.8	<.0001
Length: Long length	0.529	0.077	6.88	<.0001	0.846
Length: Medium length	0.237	0.037	6.42	<.0001	0.811
Length: Short length	Base
Fiber (continuous): Cashmere	0.0213	0.003	6.3	<.0001	0.876
Fiber (continuous): Wool	0.012	0.001	9.61	<.0001	0.766
Fiber (continuous): Standard leather	0.0115	0.001	8.62	<.0001	0.949
Fiber (continuous): Lambskin leather	0.0096	0.002	4.9	<.0001	0.95
Fiber (continuous): Suede leather	0.009	0.002	3.81	0.0001	0.977
Fiber (continuous): Gore-Tex	0.0086	0.002	5.38	<.0001	0.854
Fiber (continuous): Cotton	0.0012	0.001	2.15	0.032	0.493
Fiber (continuous): Nylon	0.0008	0	1.93	0.054	0.78
Fiber (continuous): Polyester, Rayon	Base
Brand: Exclusive	1.659	0.091	18.32	<.0001	0.684
Brand: High national	0.554	0.057	9.69	<.0001	0.815
Brand: Private	-0.147	0.041	-3.57	0.0004	0.638
Brand: Miscellaneous	-0.638	0.067	-9.49	<.0001	0.818
Brand: National	Base
Lining & Liner: Lining and liner	0.519	0.129	4.03	<.0001	0.88
Lining & Liner: Lining and no liner	0.211	0.038	5.55	<.0001	0.541
Lining & Liner: No lining and no liner	Base
Insulation: Down insulation	0.388	0.061	6.4	<.0001	0.748
Insulation: Polyester insulation	0.118	0.043	2.73	0.0064	0.684
Insulation: No insulation	Base
Sleeves: No sleeves	-0.28	0.063	-4.48	<.0001	0.89
Sleeves: Sleeves	Base
Jean Jacket: Jean jacket	-0.159	0.057	-2.8	0.0052	0.543
Jean Jacket: Not a jean jacket	Base
Waterproof: Waterproof	0.101	0.041	2.44	0.0149	0.736
Waterproof: Not waterproof	Base
Note: This model contains control variables for type of business and type of store, but they are not used in adjustments.

Summary notes

Quality adjustments derived from hedonic regressions for women’s outerwear was first incorporated into the CPI in 1997. Since then, the model has been updated eight times (including the model above).
For women’s outerwear, the characteristics that receive the most focus during model evaluation include length, fiber content, brand category (e.g., luxury, private label, etc.), and insulation (e.g., polyester or down), though other specifications can be important as well.
There are a few major differences for this model compared to previous models.
- There is a new jean-jacket style adjustment, which has not been present before. This adjustment accounts for lighter majority-cotton outerwear items to reflect their lower quality when compared to other cotton items.
- This model re-introduces a waterproof adjustment, which was not present on the most recent model in 2022.

Data

Access data for women's apparel in our online database.

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 29, 2024