Quality Adjustment in the CPI: Women’s Dresses : 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 Dresses

Item definition

Entry Level Item (ELI) category of Women’s dresses is part of the index for Women’s apparel. It includes all types and styles of dresses, jumpsuits, and rompers. In this factsheet, we examine the regression model used in the quality adjustment of price data for women’s dresses.

CPI sample

The sample used for the new hedonic model included approximately 1,880 observations from an extract of CPI data for the months of July and August 2024. There were around 75 different outlets in the sample which included a mixture of brick-and-mortar and e-commerce stores with brick-and-mortar comprising 65 percent of the sample. There were also about 450 unique clothing brands in the sample. Private brands made up about half of the sample, accounting for 48 percent of all observations, while national brands made up approximately 32 percent of the sample.

Current Model

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

Table 1. Parameter estimates for the hedonic regression for women’s dresses
Variable	DF	Parameter Estimate	Standard Error	T Value	Pr > \|t\|	Tolerance Statistic
Intercept	1	3.69575	0.02203	167.79	<.0001
Formality: Bridal	1	0.4979	0.11866	4.2	<.0001	0.64636
Formality: Formal	1	0.19003	0.03818	4.98	<.0001	0.44539
Formality: Casual		Base
Brand Category: Exclusive	1	1.61702	0.13566	11.92	<.0001	0.52026
Brand Category: Boutique	1	0.8862	0.06419	13.81	<.0001	0.70686
Brand Category: High-end national	1	0.39553	0.04479	8.83	<.0001	0.7929
Brand Category: National		Base
Brand Category: Private	1	-0.19571	0.02962	-6.61	<.0001	0.43687
Brand Category: Miscellaneous	1	-0.24141	0.0475	-5.08	<.0001	0.54205
Fiber (continuous): Wool/cashmere	1	0.00897	0.00156	5.74	<.0001	0.9267
Fiber (continuous): Silk	1	0.0072	0.00131	5.51	<.0001	0.82707
Fiber (continuous): Nylon	1	0.00203	0.00064	3.19	0.0014	0.79697
Fiber (continuous): Polyester		Base
Fiber (continuous): Cotton	1	-0.00077	0.00035	-2.17	0.0298	0.64969
Fiber (continuous): Rayon	1	-0.00082	0.00034	-2.42	0.0157	0.75191
Fiber (continuous): Spandex	1	-0.00939	0.00337	-2.79	0.0054	0.77147
Size Range: Misses or petites		Base
Size Range: Women’s plus	1	-0.12804	0.03382	-3.79	0.0002	0.81043
Size Range: Juniors	1	-0.40068	0.03915	-10.24	<.0001	0.85648
Lining: Full lining	1	0.12883	0.02733	4.71	<.0001	0.57978
Lining: Partial lining	1	0.08051	0.04179	1.93	0.0542	0.88363
Lining: No lining		Base
Length: Longer than knee length	1	0.15729	0.02167	7.26	<.0001	0.81989
Length: Knee length or shorter		Base
Sleeve Length: Long sleeve or 3/4 sleeve	1	0.11738	0.02331	5.04	<.0001	0.8351
Sleeve Length: Short sleeve or sleeveless		Base
Closure: Zipper	1	0.26915	0.02774	9.7	<.0001	0.54991
Closure: Buttons or snaps	1	0.06835	0.03034	2.25	0.0244	0.74756
Closure: No closure or other closure		Base
Details/Features: Jumpsuit or romper	1	-0.189	0.08909	-2.12	0.034	0.9575
Details/Features: Separate belt	1	0.08829	0.03301	2.67	0.0075	0.88562
Details/Features: Sequins, beads or rhinestones	1	0.19557	0.04474	4.37	<.0001	0.67649
Details/Features: No details/features		Base
Note: This model contains control variables for type of business, type of store, seasonality, country of origin, and geographic region, but they are not used in adjustments.

Summary notes

Quality adjustments derived from hedonic regressions for women’s dresses were first incorporated into the CPI in 1992. Since then, the model has been updated nine times (including the model above).
The most important specifications in evaluating substitutions for women’s dresses are formality, brand type, fiber content, and size range. All of these were included in the model.
This is the first women’s dresses model to have an adjustment for jumpsuits and rompers.
The parameter estimate for bridal dresses is lower than all previous models. The most similar bridal adjustment was 0.63732 in 2002.
The types of fiber included in the women’s dresses model have remained consistent over the years. This model contains the following exceptions:
- This model includes an adjustment for rayon, which has not appeared statistically distinct from polyester since 2000.
- Certain fibers like acetate, triacetate, and acrylic are used more rarely in women’s dresses compared to the past, resulting in them not being included in this model.
The plus size range has not been statistically significant since 2010. Maternity sizes are not included in the model and are considered non-comparable to other size ranges.

Data

Access data for Women's dresses 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: February 25, 2025