Motor Trend Car Road Tests

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Summary of the table, plot and boxplot for MPG Vs CYL:

- The highest of the mpg (miles per gallon) value levels the less cyl (number of cylinder) level that every car has.

- The lower cylinder, the high miles per gallon.

- 8 cylinder car has low mileage

- The quantities of cars that have 4 cyl much bigger than the number of cars that have 6 cyl and 8 cyl.

- The range of mpg for 6 cyl is smaller than other cyl(4 and 8).

- The highest mpg value with the lowest cyl value is Toyota corolla.

- Analysis the relation among ,mpg, am and cyl

- Fuel efficiency (analysis between Automatic and manual transmission with MPG)

- Convert the am as factor data

mtcars$am

Transmission (0 = automatic, 1 = manual)

levels(mtcars$am)

- Create a graphical visualization

> boxplot(mtcars$mpg ~ mtcars$am, data = mtcars, outpch = 17,lty=6, col="red",

lwd=2, ylab="MPG(Miles Pergallon)", col.lab="blue", col.axis="green", xlab="Transmission Type",main="MPG vs Transmission Types", col.main="brown")

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It appears that automatic cars have lower miles per gallon value means lower efficiency compare to manual transmission car which has bigger value of mpg. But we can’t directly give conclusion about that because so many factors that influence the result. So next we should test.

- To test and compare 2 sample to support this analysis, we use t-test function

t.test(mtcars$mpg~mtcars$am,)

(mpg~am) means explane by

Welch Two Sample t-test

data: mtcars$mpg by mtcars$am

t = -3.7671, df = 18.332, p-value = 0.001374

alternative hypothesis: true difference in means is not equal to 0

95 percent confidence interval:

-11.280194 -3.209684

sample estimates:

mean in group Automatic mean in group Manual

17.14737 24.39231

The t.test describe many things:

- T.test show that the p-value (0.001374) is low means there is an actual difference between groups.

- Mpg of manual cars is greater than automatic cars, and we can take a look from the evidence of hypothesis. 95% bring about the interval lies completely below 0, indicated that the difference between mpg of manual cars and automatic cars are negative.

- The mean of manual cars bigger than automatic cars means the manual is better than manual cars in mpg (efficiency).

- Analysis between mpg, am and cyl

library(ggplot2)

library(gridExtra)

mtcars$am

levels(mtcars$am)

par(mfrow = c(2,2))

plot2_3a

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fit

summary(fit)

bestfit

plot2_3b

anova(fit, bestfit)

summary(bestfit)

aggregate(mpg~am*cyl, data=mtcars, mean)

[pic 9]

The summary:

- For the 4 cylinders cars, manual cars has higher value of mpg and bigger range for miles per gallon than autimatic cars. This means the manual cars with 4 number of cylinders are the most efficient cars.

- For the 6 cylinders cars, automatic cars have bigger range or miles per gallon but with the lower value than manual cars. This mean at this point the number of manual cars that had 6 cyliders smaller number than the automatic but more efficient that automatics because the average value that manual cars spend on fuel higher than automatic.

- For the 8 cylinders cars, automatic have much bigger on amount than manual, and the range of mpg that automatics cars has higher than the manual but the average that both cars spend on fuel is roughly the same.

- The most efficient cars is manual cars with 4 cylinder

- The manual cars is better than automatic cars in all kind of cylinders, because nomatter how many the number of cylinder mmanual cars always has a good number of mpg value.

- Manual cars is most efficient

- Transmission and cylinder effect the mpg value

- you can analysis data and get more conclusions

- The analysis between MPG with WEIGHT(wt)

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The analysis about relationship between mpg with weight is analysis can be concluded that:

- Mostly cars with heavy weight spend more gallons of fuel compared with a car that not heavy cars (light). Means that the higher the weight of car the lower fuel efficiency.

- Other words heavy cars have small value of mpg compared to lighter cars which have much bigger in mpg value.

- The heaviest car will spend 1 gallon of fuel only for 10.4 miles is Lincoln Continental.

2. Use the cor

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