knowledge: diamonds

This data set is a sampling of 617 round shape diamonds collected from retail website in December 2007. The data includes the following variables for each diamond: Price, Carats, Clarity, Color, Cut, ClarityCode, ColorCode, CutCode.

Source

Blue Nile Website

Summary

Rows 617

Columns 8

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Initial (20.5 kb) Dec 13, 2007

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Data Summary

Showing last 6 rows and first 4 columns

Price	Carats	Clarity	Color	Cut	ClarityCode	ColorCode	CutCode

$2,177.00	0.5	VVS1	F	Ideal	6	5	3
$3,361.00	0.78	VVS2	G	Ideal	5	4	3
$1,795.00	0.51	VS1	F	Ideal	4	5	3
$3,023.00	0.7	VS1	F	Ideal	4	5	3
$9,821.00	1.26	VS2	F	Ideal	3	5	3
$2,137.00	0.82	SI2	J	Ideal	1	1	3
more...	more...	more...	more...	more...	more...	more...	more...

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Recent Comments

robschoen

robschoen says

I used this data to do a regression model for estimating the value of a round shaped diamond based on its weight, clarity, color, and cut.

The model I came up with was:

log(price) = 7.784 + 2.032*log(carats)
+0.113*clarityCode + 0.102*colorCode + 0.030*cutCode

This model has an adjusted R-squared of .96. The remaining variance is possibly explained by some additional factors not included in the dataset, such as symmetry, polish, and fluorescence. I tried using dummy variables for each of the codes, but was surprised how little this increased the model's explanatory power.

It's a log-model, so the errors are larger in absolute dollars when estimating more valuable dollars, but the percentage size of the errors is fairly consistent.

posted 10 months ago

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