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

Quality Adjustment in the CPI: Men’s Boots, Shoes, Sandals, and Slippers

Item definition

Men's footwear image

The Entry Level Item (ELI) category of Men’s Footwear is part of the index for Footwear. It includes two categories: (1) men’s casual or dress shoes, boots, sandals, and house slippers, and (2) men’s athletic footwear. Here, we examine the hedonic regression model used in the quality adjustment of price data for the first group, men’s boots, shoes, sandals, and slippers.

CPI sample

The sample used for the current hedonic model for men’s boots, shoes, sandals, and slippers included 645 observations from an extract of CPI data for the months of August and September 2022. The model was constructed using web-based information due to restrictions on data collection during the COVID-19 pandemic, unlike models from the past that had a mix of store and website data. There were more than 225 unique brands in the sample, with most brands having fewer than 20 observations. Additionally, the sample included more than 100 outlets of both the brick and e-commerce variety; the top outlet was about 7 percent of the sample.

Current Model

Table 1 presents the details of the estimation of the current model used to quality adjust men’s boots, shoes, sandals, and slippers.

Table 1. Parameter estimates for the hedonic regression for men's footwear
Variable Name DF Parameter Estimate Standard Error T Statistic Pr > |t| Tolerance Statistic

Intercept

 1 4.57512 0.04264 107.3 <.0001

Type: Sandal

 1 -0.51291 0.05203 -9.86 <.0001 0.67065

Type: Slipper

 1 -0.46279 0.06182 -7.49 <.0001 0.801

Type: Above mid-calf to knee boot

 1 0.58161 0.09716 5.99 <.0001 0.88231

Type: Above ankle to mid-calf boot

 1 0.23491 0.04582 5.13 <.0001 0.68167

Type: Ankle boot

 1 0.17784 0.05455 3.26 0.0012 0.83029

Type: Shoe

 Base

Upper Material: Man-made upper

 1 -0.56605 0.04409 -12.84 <.0001 0.60878

Upper Material: Fabric upper

 1 -0.34092 0.05963 -5.72 <.0001 0.75176

Upper Material: Combination upper

 1 -0.17793 0.05742 -3.1 0.002 0.81096

Upper Material: Leather upper

 Base

Outsole Material: Leather outsole

 1 0.23729 0.08073 2.94 0.0034 0.9114

Outsole Material: Part leather, part man-made outsole

 1 0.20579 0.06877 2.99 0.0029 0.93224

Outsole Material: Man-made outsole

 1 Base

Brand Category: Exclusive

 1 1.2592 0.13232 9.52 <.0001 0.81081

Brand Category: High/premium national

 1 0.22469 0.05404 4.16 <.0001 0.89101

Brand Category: Private

 1 -0.08961 0.04533 -1.98 0.0485 0.83146

Brand Category: Miscellaneous

 1 -0.46271 0.10931 -4.23 <.0001 0.93808

Brand Category: National

 Base

Rainboot

 1 -0.28428 0.09804 -2.9 0.0039 0.91317

Electrical hazard protection

 1 0.31639 0.0715 4.43 <.0001 0.80196

Note: This model contains control variables for type of business, type of store, and geographic region, but they are not used in adjustments.

Summary notes

  • Quality adjustments derived from hedonic regressions for men’s boots, shoes, sandals, and slippers were first incorporated into the CPI in 1995. Since then, the model for men’s boots, shoes, sandals, and slippers has been updated five times.

  • For men’s boots, shoes, sandals, and slippers, the characteristics that receive the most focus during model evaluation include footwear type, upper material, outsole material, and brand category, though other specifications can be important as well.

    • Some footwear hedonic models have adjustments for specific brands, but this data did not demonstrate a need for that given the diversity of the sample.

    • The model for men’s boots, shoes, sandals, and slippers has been relatively stable over the years when compared to some other ELIs. The four specifications listed above have always been included.

Data

Access data for Footwear 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: June 30, 2023