NAME: Diamond Ring Pricing Using Linear Regression TYPE: Random sample SIZE: 48 observations, 2 variables DESCRIPTIVE ABSTRACT: This dataset contains the prices of ladies' diamond rings and the carat size of their diamond stones. The rings are made with gold of 20 carats purity and are each mounted with a single diamond stone. SOURCE: The source of the data is a full page advertisement placed in the _Straits Times_ newspaper issue of February 29, 1992, by a Singapore-based retailer of diamond jewelry. VARIABLE DESCRIPTIONS: Columns 6 - 8 Size of diamond in carats (1 carat = .2 gram) 16 - 19 Price of ring in Singapore dollars Values are aligned and delimited by blanks. There are no missing values. STORY BEHIND THE DATA: Data presented in a newspaper advertisement suggest the use of simple linear regression to relate the prices of diamond rings to the weights of their diamond stones. The intercept of the resulting regression line is negative and significantly different from zero. This finding raises questions about an assumed pricing mechanism and motivates consideration of remedial actions. PEDAGOGICAL NOTES: This dataset can be used to illustrate model-building in linear regression. A possibly counter-intuitive negative intercept may be avoided by using a multiplicative or exponential regression model. These regression models are intrinsically linear, and they are estimated using standard linear regression technology after a suitable transformation of the data. Additional information about these data can be found in the "Datasets and Stories" article "Diamond Ring Pricing Using Linear Regression" in the _Journal of Statistics Education_ (Chu 1996). SUBMITTED BY: Singfat Chu Department of Decision Sciences National University of Singapore 10 Kent Ridge Crescent Singapore 119260 fbachucl@nus.sg