Datasets for Statistical Analysis

Computer disc media

Keywords:

computer; CD; DVD; disc; disk; price

Categories:

regression;
popular

Description:

The price of CDs, DVD-Rs and DVD+/-RWs were obtained from a Choice magazine study of reliability of computer media. The discs were purchased by Choice magazine in April 2005 in multi-packs (the small number of individual purchases of discs were discarded). The brand names, though reported by Choice, are not given.

There are 28 observations on three variables.

Variables:

price	The price per disc in Australian dollars paid by Choice in April 2005
pack	The pack size: the number of disc in the pack
media	The type of media: one of CD (CD), DVD (DVD-R) or DVDRW (DVD+/-RW)

Data Quality:

There are no missing values.

Source:

Choice magazine webpage, accessed 28 July 2005.

Notes:

One can fit a regression model. media is, unsurprisingly, highly significant, pack mildly significant, and the interaction (perhaps surprisingly) insignificant. The main lesson is in interpretation: what do the intercept and slope mean? How can they be interpretted? A residual plot shows heteroscedasticity; a log transform (or gamma glm) seems necessary.

References: