We analysed the dataset using Spotfire .
We observed some interesting relationships among various attributes of
a car, and saw how its efficiency depends on factors like number of cylinders
, weight, etc.
As the number of cylinders increases, higher horsepower is obtained. Cars
with 8 cylinders have maximum horsepower. The graph also shows a
tendency towards manufacturing cars with even number of cylinders in
comparison to ones with odd number of those. In fact, there are only a few
cars which have 3 or 5 cylinders.
The relationship is inverse. Higher horsepower is obtained by using greater
number of cylinders in the car. But that increases the weight of the car.
Hence, we get lower MPG.
The plot shows that in late 70s and early 80s, there was an increasing
emphasis on getting higher MPG cars. Consequently, the number of eight
cylinder cars decreased since they gave poor MPG. Moreover, we can see
a clear shift in focus to 4 cylinder cars.
This is a good example of separation of data into different categories.
The plot clearly shows that three cylinder cars were produced only by the
Japanese, 5 cylinder cars only by Europeans, and 8 cylinder cars only by
Americans. This indicates an initial emphasis in the US on cars with
greater horsepowers, which later shifted to cars with lower MPG.
The plot shows an almost linear relationship. There is a single outlier
- buick estate wagon - which has high horsepower and medium weight. Due
to this, it performs extremely well on MPG, and gives very low times
to accelarate.