In the 1974 Motor Trend US magazine came out with Data which comprises fuel Consumptions and 10 other aspects of automobile performance.
Question
Does MPG depend on transmission type (automatic vs. manual)?, If so, which is better for MPG? Quantify the MPG difference between automatic and manual transmissions.
Findings
Mileage (mpg), when modeled with just one predictor am, we get manual transmission to yield an average of 7.245mpg higher than automatic transmission. Here, only 33.85% of variance could be explained.
Multiple regression on stepwise regressed variables defines 83.36% of variability. wt and qsec have confounded the relationship between am and mpg. Manual transmission in this model increases mileage by only 2.936 mpg
- mtcars dataset https://stat.ethz.ch/R-manual/R-devel/library/datasets/html/mtcars.html
- Density Plot. http://www.statmethods.net/graphs/density.html
- Analysis on mtcars dataset to predict mpg http://varianceexplained.org/RData/code/code_lesson3/
- BoxPlot using ggplot2 http://www.statmethods.net/advgraphs/ggplot2.html
- More on factors http://www.stat.berkeley.edu/~s133/factors.html
- Confounding Variables http://en.wikipedia.org/wiki/Confounding/
- two-sample t test http://www.isixsigma.com/tools-templates/hypothesis-testing/making-sense-two-sample-t-test/
- Coursera regmods https://github.com/sefakilic/coursera-regmods/