Grouping The Data
Due to my population size, grouping the gathered data is essential. As I mentioned earlier, I will divide the cars into two groups, Large and small engined cars, excluding all anomalous data and disproportionate values.
Here is my Grouped Data
Required Information
In order to carry out my investigation, I will need more information based upon the average percentage depreciation in value of the cars per year. As this would take much time to work out, I have devised a spreadsheet to do it. I have also removed all anomalous data. To do this, I used the calculation (a-b)/c=x(depreciation per year in pounds) , where ‘a’ is the original value of the car in pounds, ‘b’ is the second hand value of the car in pounds and ‘c’ is the age of the car in years. This gave me the average depreciation per year in pounds per year. To obtain the percentage depreciation in value per year I used this formula (x*100)/a=n(average percentage depreciation per year). To display this, I created two extra fields in the data I accumulated earlier.
Average percentage depreciation per year of small engined cars
Average percentage depreciation per year of large engined cars, is greater than that of the small engined cars which shows that larger engined cars depreciate at a greater rate than small engined cars, thus prooving that my theory is correct.
Average percentage depreciation per year of small engined cars
Average percentage depreciation per year of large engined cars
Small Cars (Engines less than or equal to 1.4 litres)
Large Cars (Engines above 1.4 litres)
In general, larger engines appear to be more frequent and engine sizes, whilst they increase at a steady rate exclude many values, for example jump from 1.6l to 1.8l. Perhaps simple flaws like this could have been avoided through assembling a greater population.
Mean Engine Size
Small=0.95l
Large=2l
Combined=1.5
Modal Engine Sizes
Small=s = 1.4l
Large=2.0 ≤ s<2.1
Combined= s = 1.4l
Median Engine Sizes
Small= 1.3l
Large= 1.8
Combined= 1.6l
Mean Depreciation per Year
Small=£1220.9
Large=£2747.472
Combined=£2003.008789
Mean Percentage Depreciation per Year
Small=13.08985054
Large=15.92041518
Combined=14.5400781
Fair Comparison
As you can see above, There are more large engined cars in my investigation thus far than small engined cars, this gives inaccurate data, and so I must eliminate a few of my results for large engined cars so as to have an equal proportion of large to small engined cars. I have removed 4 completely random pieces of data from the group of large engined cars so that both groups now have 77 entries creating a fair comparison.
Small Engined Cars
Large Engined Cars
I have decided to present this data on a cumulative frequency graph, this is because it will give clear visual confirmation of which group did in-fact hold its value better (depreciate at a lesser rate). Also I could easily take averages and other such data from this which I could then use to draw up other graphs such as box plots and Histograms.
Comparing Box Plots
I am comparing two box plots, in order to obtain a result prove up or disprove my original hypothesis that small cars hold their value better than large engined cars. The box plot I have drawn for the small engined cars has a lower average than that of all the engine sizes and, more importantly the large engined cars which partially proves my hypothesis, it also has a shorter inter-quartile range than the pair. The large engined cars results are all higher or greater than the average which also gives evidence to support my hypothesis.
Conclusion
These sets of data have shown that, while my initial hypothesis is correct, it is not a huge difference in the average depreciation per year of cars dependant uipon their various engine sizes. This means that it is pheasable for small and large engined cars depreciate at approximately the same rate, so something else must be affecting the outcome of my results. Other factors affecting the depreciation of automobiles could include: insurance costs, condition, colour, whether or not it has an MOT, economy, collectability and status.
In the future, I could expand this investigation to include any of the above factors and so determine what the sole governing factor affecting the depreciation of an automobile is, if it is not its age, however the small difference between the depreciation of large and smell engened cars that my investigation has shown may still be the greatest factor effecting the depreciation of cars, but this is still to be determined through further investigations in to the factors affecting the depreciation of cars..
