Statistics Project Linear Relationship [Car Acceleration vs. Engine Displacement] (SPSS)
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Transcript of Statistics Project Linear Relationship [Car Acceleration vs. Engine Displacement] (SPSS)
Rudranath Ghorai
GDGWI ID: 120232
Programme: BBA – BS (2012-2015)
Module: MNGT213
Module Leader: Kim Menezes
Word Count: ~2000
MNGT213
COURSEWORK
PROJECT
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RESEARCH OBJECTIVE DOES HAVING A CAR WITH A BIG ENGINE DISPLACEMENT MEAN THAT IT WOULD PROVIDE BETTER ACCELERATION?
INTRODUCTION
A car engine uses small controlled explosions to create the power needed to move the
vehicle. All car engines use a four stroke combustion cycle. The four strokes are intake,
compression, combustion and exhaust.
Power is generated when these strokes repeat in quick succession. All parts of the
combustion cycle take place within an enclosed car engine.
The core part of an engine, the pistons, are enclosed in cylinders. When the pistons are
moved up & down by the crankshaft, the vehicle is put into motion.
Engine displacement is the volume swept by the pistons in the cylinders. It’s generally
measured in cubic inches (cu in), litres (L) or cubic centimetres (cc).
The engine displacement can be calculated with the formula given below:
Displacement = (π/4) x bore2 x stroke x number of cylinders
The acceleration of a car is found out by the time taken by the car to reach from 0-100
km/h.
DATA DESCRIPTION
A sample of the world’s fastest cars were handpicked. Engine displacements were given
for each car & I had to manually find the acceleration i.e. time taken by the car to reach from 0-
100 km/h.
For the assignment, I found the engine sizes in different measurement units, so in order
to achieve consistency, I converted them into cc. “Car” denotes the make & model of the car,
“Time” is the time taken by the car in seconds to reach from 0 km/h to 100 km/h & “Engine
Displacement” denotes the engine capacity in cubic centimetres.
The car names are qualitative nominal data whereas engine displacement & time are
quantitative ratio data. The data collected is cross-sectional data.
ANALYSIS
The data used in the assignment has been analysed with IBM SPSS & Microsoft Excel.
Using the data, necessary tables & graphs were created to support the purpose of the analysis.
The scatter plot diagram illustrates the degree of co-relation & regression between the two
variables, engine displacement & time. The histograms illustrate the frequency of time & engine
displacement.
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Car Time (seconds) Engine Displacement (cc)
Bugatti Veyron 16.4 Super Sport 2.7 7993
Chevrolet Corvette C6 ZR1 3.4 6200
Dodge Viper SRT-10 2.3 7996
Ferrari 430 Scuderia 4.25 4300
Ferrari 458 Italia 4.3 4424
Ferrari 599 GTO 3.54 5999
Ferrari Enzo 3.8 6000
Ferrari F12 Berlinetta 2.8 6262
Gumpert Apollo Sport 4.15 4260
Jaguar F-Type V8 S 3.6 5000
Koenigsegg Agera R 3.5 4998
Koenigsegg CCX 3.65 4800
Koenigsegg CCXR 3.95 4700
Koenigsegg CCXR Edition/Trevita 3.6 4800
Lamborghini Aventador 2.46 6498
Lamborghini Gallardo LP560-4 3.4 5243
Lamborghini Murciélago LP640 3.1 6200
Lamborghini Superleggera 3.7 5243
Lamborghini SuperVeloce 2.9 6496
McLaren F1 3.35 6100
McLaren MP4-12C 4.79 3800
Mercedes-Benz CLK GTR 3.47 6063
Mercedes-Benz SLR McLaren 3.85 5400
Mercedes-Benz SLS AMG 3.3 6200
Nissan GT-R R35 4.63 3799
Pagani Huayra 3.5 5980
Porsche 911 GT3 4.58 3600
Porsche 911 Turbo S 5.1 3596
Porsche 918 Spyder 4.05 4600
SSC Ultimate Aero TT 3.2 6350
Observations Time (seconds) Engine Displacement (cc)
Mean 3.630666667 5430
Median 3.57 5321.5
Mode 3.4 6200
Standard Deviation 0.667646062 1155.104026
Variance 0.430892889 1289789.8
Range 2.8 4400
Minimum 2.3 3596
Maximum 5.1 7996
Sum 21.89920562 1323888.404
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25 3.275 4556
Percentiles 50 3.6 5243
75 4.125 6200
First Quartile 3.275 4556
Third Quartile 4.125 6200
Mode 3.4 6200
IQR 0.85 1644
From the above data we can see that the mean for the engine displacement is 5430 &
median is 5321.5. The minimum value is 3596 cc for Porsche 911 Turbo S & the maximum value
is 7996 cc for Dodge Viper SRT-10. The range is 4400, standard deviation is 1155.104026 &
variance is 1289789.8.
Similarly, for time, the mean is 3.630666667 & median is 3.57. The minimum value is
2.3 seconds for Dodge Viper SRT-10 & the maximum is 5.1 seconds for Porsche 911 Turbo S. The
range is 2.8, standard deviation is 0.667646062 & variance is 0.430892889.
Since both the variables possess extreme values, the best way to go about computing the
range would be by using Inter-Quartile Range (IQR).
The reason why we use IQR is because it excludes extreme values on both ends & takes
into consideration only the middle 50% values.
IQR for Engine Displacement: 6200 – 4556 = 1644 cc
IQR for Time: 4.1 – 3.275 = 0.825 seconds
The range for engine displacement was 4400 & IQR comes out at 1644 cc & for time,
range was 2.8 & IQR for it comes out 0.5 seconds. We can see that there is a considerable
difference between the ranges & IQRs of both the variables.
For engine displacement, the mode is 6200 cc (Chevrolet Corvette C6 ZR1, Lamborghini
Murciélago LP640, Mercedes-Benz SLS AMG) & for time, it’s 3.1 seconds (Lamborghini
Gallardo LP560-4 & Ferrari 599 GTO).
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After taking a close look at both the histograms, we can conclude that the time histogram is right skewed & the engine histogram is left skewed.
For variable “time”, the majority of data lies in between 3-4 seconds & for variable
“engine”, the maximum data lies in 6000-7000 cc. One thing to note over here is that in the engine histogram, there is no data between 6500-7500 cc however there is one observation at 7500+ cc.
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Engine
Frequ
ency
% Valid
%
Cumulative
%
Valid
3596 1 3.3 3.3 3.3
3600 1 3.3 3.3 6.7
3799 1 3.3 3.3 10.0
3800 1 3.3 3.3 13.3
4260 1 3.3 3.3 16.7
4300 1 3.3 3.3 20.0
4424 1 3.3 3.3 23.3
4600 1 3.3 3.3 26.7
4700 1 3.3 3.3 30.0
4800 2 6.7 6.7 36.7
4998 1 3.3 3.3 40.0
5000 1 3.3 3.3 43.3
5243 2 6.7 6.7 50.0
5400 1 3.3 3.3 53.3
5980 1 3.3 3.3 56.7
5999 1 3.3 3.3 60.0
6000 1 3.3 3.3 63.3
6063 1 3.3 3.3 66.7
6100 1 3.3 3.3 70.0
6200 3 10.0 10.0 80.0
6262 1 3.3 3.3 83.3
6350 1 3.3 3.3 86.7
6496 1 3.3 3.3 90.0
6498 1 3.3 3.3 93.3
7993 1 3.3 3.3 96.7
7996 1 3.3 3.3 100.0
Total 30 100.0 100.0
Time
Frequency % Valid
%
Cumulative
%
V
a
l
i
d
2.30 1 3.3 3.3 3.3
2.46 1 3.3 3.3 6.7
2.70 1 3.3 3.3 10.0
2.80 1 3.3 3.3 13.3
2.90 1 3.3 3.3 16.7
3.10 1 3.3 3.3 20.0
3.20 1 3.3 3.3 23.3
3.30 1 3.3 3.3 26.7
3.35 1 3.3 3.3 30.0
3.40 2 6.7 6.7 36.7
3.47 1 3.3 3.3 40.0
3.50 2 6.7 6.7 46.7
3.54 1 3.3 3.3 50.0
3.60 2 6.7 6.7 56.7
3.65 1 3.3 3.3 60.0
3.70 1 3.3 3.3 63.3
3.80 1 3.3 3.3 66.7
3.85 1 3.3 3.3 70.0
3.95 1 3.3 3.3 73.3
4.05 1 3.3 3.3 76.7
4.15 1 3.3 3.3 80.0
4.25 1 3.3 3.3 83.3
4.30 1 3.3 3.3 86.7
4.58 1 3.3 3.3 90.0
4.63 1 3.3 3.3 93.3
4.79 1 3.3 3.3 96.7
5.10 1 3.3 3.3 100.0
Total 30 100.0 100.0
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The above scatter plot diagram illustrates a negative bivariate linear regression. It means that there are two variables, “engine” is the independent variable & “time” is the dependent variable & collectively they have a negative slope.
The dependent variable “time”, on the Y-axis is to be predicted whereas the independent
variable “engine” on the X-axis is the predictor. Correlation is a measure of the degree of relatedness of two variables.
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We can further elaborate our findings with the help of a hypothesis test.
The simple linear regression model is:
Variables Entered/Removeda
Model Variables
Entered
Variables
Removed
Method
1 Engineb . Enter
a. Dependent Variable: Time
b. All requested variables entered.
Model Summary
Model R R Square Adjusted R
Square
Std. Error of the
Estimate
1 .916a .839 .833 .27252
a. Predictors: (Constant), Engine
ANOVAa
Model Sum of Squares df Mean Square F Sig.
1
Regression 10.847 1 10.847 146.054 .000b
Residual 2.080 28 .074
Total 12.927 29
a. Dependent Variable: Time
b. Predictors: (Constant), Engine
Coefficientsa
Model Unstandardized Coefficients Standardized
Coefficients
t Sig.
B Std. Error Beta
1 (Constant) 6.506 .243 26.768 .000
Engine -.001 .000 -.916 -12.085 .000
a. Dependent Variable: Time
Expected Time: 6.506 - .001 x Engine Displacement
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Assuming a 95% confidence interval, α = 0.05. Since the p value is less than α ie. 0.05,
we can reject H0. This proves that the engine displacement does influence the acceleration of a
car.
Since R2 = .839, we can state that 83.9% of the variation in time taken for a car to go
from 0-100 km/h is explained by the regression of the time taken to reach 0-100 km/h on the
engine displacement.
From the linear equation above, we can derive that for every increase in engine
displacement size, the estimated time for a car to go from 0-100 km/h will decrease by 0.001
seconds.
Another interesting aspect about this analysis is that the standard error is 0.000. This
means that the engine size is a major determinant of time taken by the car to reach 0-100 km/h.
However there are certain values that do not fall on the regression line. This could be due
to an array of other factors such as mass of the car, brake horsepower (bhp), torque, number of
cylinders, make of engine, etc.
In the case of Lamborghini Aventador, it weighs 1,575 kg & Bugatti Veyron 16.4 Super
Sport weighs 1,888 kg. Aventador gives an acceleration of 2.46 seconds whereas Veyron gives an
acceleration 2.7 seconds given the fact that Veyron has an engine displacement of 7993 cc
whereas Aventador has an engine displacement 6498 cc. Even though the Veyron has a more
powerful engine, Aventador has a lighter chassis & that gives an edge in terms of acceleration.
This is a clear example which shows how much a car’s weight has influence on its acceleration.
From Newton’s formula, Force = Mass x Acceleration, shifting sides, the formula
becomes, Acceleration = Force/Mass.
So when mass of a car increases, it has an inverse effect on the acceleration & hence
acceleration reduces.
CONCLUSION To sum it up, the engine displacement of a car plays a major role in the rate of
acceleration of a car, however it is not the only factor on which acceleration is dependent.
Other factors which affect acceleration is the type of engine. In the case of a diesel
engine, it tends to have a slow pickup & then it gives a sudden push. However, a petrol engine
gives a full pickup since the very moment you press the throttle. Aerodynamics of a car also play
a major role in the acceleration of a car.
Lastly, the weight of the car also plays a major role. As said previously, Aventador &
Veyron had an engine displacement of 6498 cc & 7993 cc respectively but due to the weight
differences & Aventador had a better acceleration over Veyron considering the fact that the
latter had a more powerful engine.
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From a personal point of view, there was a steep learning curve associated with learning
how to use IBM SPSS. I had to spend hours on YouTube learning SPSS & then figuring out how
to read the regression chart it threw at me.
New programs to explore, bundled with a lot of new statistical terminologies did make
the whole process a bit too overwhelming, but the entire experience of learning something &
knowing someday it’s going to help you in the near future made up for all of the hard work that
went into this assignment.
It’s every car aficionado’s dream to own at least one of the cars mentioned in the
observation set. The fact that owning even one of the cars would require millions of dollars,
keeps me daydreaming about them.
Till then, it’s safe to say, “Speed thrills, but kills.”
BIBLIOGRAPHY TopCarRating. (2013). The fastest cars in the world. The highest speed. Top rated
maximum speed of supercars.. Available: http://www.topcarrating.com/topspeed.php. Last
accessed 25th Nov 2013.
TheSuperCars. (2013). Fastest Cars In The World: Top 10 List 2013-2014. Available:
http://www.thesupercars.org/fastest-cars/fastest-cars-in-the-world-top-10-list/. Last
accessed 25th Nov 2013.