First Line of Enquiry: My first line of enquiry is going to be Make. I will go about this by first grouping all my cars up according to there make. Then I will work out there average cost, meaning the average cost of the individual Make. This will basically allow be to compare all the makes average prices and so come up with the most expensive and least expensive makes. I am aware of the disadvantages of this method, as going through with this method will mean that I am giving all the makes a price. But I think it is an effective way to categorise my sample, and to obtain the results representative of all the makes. I am also aware that the model number will also have an affect on the price of the car but in this part of the investigation I have
chosen to only include the make as I want my results to be only representing the effect of make on the price of a car, nothing else.
The table on the left shows the cost of the average car from a make, according to my sample. As you can see ford is the least expensive of the makes as average price of its car is only £6,864. Where as Bentley is the most expensive with its average car coming up to £170.841. I am aware that these figures are not a real representative of these companies in general but these figures are a true representative of all the cars which I choose to investigate, making the figures very useful and important as they show the amazing difference in the make and price of a car, proving that Make is one of the factors that affect the price of a car.
Interpretation of Graph: Looking at the graph you can clearly see that the makes have a major affect on the price of most cars. So by looking at the graph you can see that one of the major factors which influence the price of a car is its make.
Second Line of Enquiry: My second line of enquiry will be age, I will investigate the same group of cars again and this time try to prove that as the age increases the percentage depreciation in general also increases. For this I will simply put all of my cars in order of age and then draw up a scatter diagram of them, this will allow me to see the pattern between the age of the car and the percentage depreciation. I am aware that there might be some anomalies the simple reason for this is because age is not the only factor that affects the percentage depreciation like I have already proved; Make is also a major factor in the value of a car. So if a car of a good make such as BMW is 5 years old it will still depreciate less then a car of say Ford which is also five years old. I predict that in general as the age increases the average depreciation will also increase.
Interpretation of Graph: Looking at the graph you can see that there is a strong correlation between the age and the percentage depreciation. As I predicted the percentage depreciation increases as the age increases, meaning that the Age is also a major factor in the value of a car. The reason for the anomalies in my graph is that age is not the only factor which affects the percentage depreciation, but as most of my cars fit the pattern I conclude that there is a strong link between the age and the percentage depreciation and that as the age increases the percentage depreciation also increases for most cars.
My Extension: Now that I have finished my Age and Make investigation, like I said before one of the things that are unknown to me is does the make of the car affect the percentage depreciation. So now I will aim to find an answer to that question, I am going to divide all the cars into three main categories. The low-priced makes, the medium priced makes and the expensive makes. After doing this I am going to test if all the makes depreciate by the same amount as they get older. By finding this out, I will also find out if make has a big role ion the percentage depreciation of a car or not.
My Hypothesis is that the expensive makes will depreciate slower then the medium priced makes and the medium priced makes will depreciate slower then the low-priced makes. I think that the expensive makes would have a bigger gap between there depreciation and there age, then low-priced makes which will have a smaller difference between there depreciation and there age. For example I think that if an expensive make was 5 years old and its % depreciation was 25%. A low-priced make with the same age 5 years old, would have a bigger difference in its percentage depreciation say 55%.
The table above shows how I have categorised the cars for the group that is the low-priced group. I have chosen the suitable makes with high depreciation making them the low-priced group. From this I have found the cumulative frequency for each percentage depreciation groups and then put the cars into their groups e.g. 40%-60% etc. The best way to show my results would be in the form of a cumulative frequency graph, so I made one.
The table above shows how I have categorised the cars for the group that is the medium priced group. I have chosen the suitable makes with medium depreciation making them the medium-priced group. From this I have found the cumulative frequency for each percentage depreciation groups and then put the cars into their groups e.g. 40%-60% etc. The best way to show my results would be in the form of a cumulative frequency graph, so I made one.
The table above shows how I have categorised the cars for the group that is the expensive priced group. I have chosen the suitable makes with low depreciation making them the medium-priced group. From this I have found the cumulative frequency for each percentage depreciation groups and then put the cars into their groups e.g. 40%-60% etc. The best way to show my results would be in the form of a cumulative frequency graph, so I made one.
Basically now that I have drawn all the cumulative frequency diagrams, in other words in other words graphs which compare the percentage depreciation to the count rate of all the makes. I can draw conclusions from these graphs by comparing the median, upper quartile, lower quartile, and the inter quartile range. To make this easier I will draw 3 box plots, one for each type of make.
The box plot for the expensive makes…
The box plot for the medium priced makes…
The box plot for the low-priced makes…
(The bottom percentages on all the box plots represent percentage depreciation)
By looking at the box and whisker diagrams we can see that…
- Both the medium and maximum ranges of the expensive make are greater then the low-cost and the medium makes. Indicating that the expensive make is the most spread out meaning that it has a wide range.
- The less expensive and medium makes have a higher depreciation median, meaning that the less expensive and medium makes have a higher depreciation on average then the expensive makes.
- The less expensive makes have the highest second 75% meaning that more of there cars are in higher depreciation compared to the expensive and medium makes.
Overall the lower priced makes had the highest median meaning that like I predicted more of the low-priced makes had a higher depreciation compared to the expensive and medium makes. The expensive makes had the largest range and so therefore there range is the most spread out meaning that more of there cars were in the lower/median quartile then any other make. Meaning that like I predicted the expensive make cars were the ones with the least amount of depreciation in general! And the least expensive makes were the most depreciated in general!
Conclusion
As a result of this investigation I now know that the two main factors that affect the average depreciation of a car, in other words the two main factors which affect the cars prices are Age and Make. I have proved this in my investigation with the use of several diagrams, tables and results that back up my claims. Thus my predictions and hypothesis’s were correct and one of the first things I found out was that the age of the age affects the percentage depreciation, the older the car is the more it will depreciate by. This was supported by my scatter graph which showed a strong positive correlation between age and increase in percentage depreciation.
Overall I think that my investigation was pretty successful because of the results I obtained and also due to the fact that my hypothesis and predictions were proven correct. Although I do think that there are a few things I could have improved on for example I could have gone out and collected my own sample of second hand and new cars, I could have had an equal amount of expensive, medium and less-expensive makes making my investigation more accurate. I could have also investigated other factors such as the mileage and come up with a more in depth result of the factors which affect a cars price and why…