Regression of the Diamond Data
In this activity, you will 
be performing a linear regression analysis to
see if diamond prices from the Singapore diamond exchange can be predicted from the weight
of diamonds. Though it seems intuitively obvious that the bigger the diamond, the more it
will cost, could there be other factors
influencing the value just as much as size? Using either Excel
or the TI-83 graphing calculator, perform a linear
regression to determine if there is a substantial correlation between the weight and value
of a diamond and if predicting diamond prices from their weight is a viable option. 
This data exists in three files; one is in Excel Data format, one is in Text format, and one is in TI-83 Group format. If you want to perform the linear regression using the TI-83, you will have to import the text data into the calculator from the computer after you have downloaded the file.
Are most of the data points close to the least squares regression line? What is the r-value (correlation coefficient)? What is the regression equation? Using the equation, do you think you could accurately predict the price of a diamond sold at the Singapore diamond exchange? Are there any other factors influencing the price of a diamond?
Original work on this document was done by Central Virginia Governor's School students Stephanie Mayer, Teona Callaham, and Nam Tran (Class of '98).
Copyright © 1997 Central Virginia Governor's School for Science and Technology Lynchburg, VA