6.12 Chapter 6 Review Questions

We're going to be referring to a data frame called mpg. It contains a subset of the fuel economy data that the EPA makes available on fueleconomy.gov. It contains only models which had a new release every year between 1999 and 2008—this was used as a proxy for the popularity of the car. Below is a portion of the data, including definitions of the variables used in it.

 manufacturer model displ  year   cyl trans      drv     cty   hwy fl    class
1 audi        a4     1.80  1999     4 auto(l5)   f        18    29 p     comp~
2 audi        a4     1.80  1999     4 manual(m5) f        21    29 p     comp~
3 audi        a4     2.00  2008     4 manual(m6) f        20    31 p     comp~
4 audi        a4     2.00  2008     4 auto(av)   f        21    30 p     comp~
5 audi        a4     2.80  1999     6 auto(l5)   f        16    26 p     comp~
6 audi        a4     2.80  1999     6 manual(m5) f        18    26 p     comp~

• manufacturer Manufacturer/brand name
• model Car model name
• displ Engine displacement, in litres
• year Year of manufacture
• cyl Number of cylinders
• trans Type of transmission
• drv f = font-wheel drive, r = rear wheel drive, 4 = 4wd
• cty City miles per gallon
• hwy Highway miles per gallon
• fl Fuel type. e = ethanol, d = diesel, r = regular, p = premium c = natural gas
• class The "type" of car