"The price of a silver used car will be higher then that of red and blue used cars"

Statistics to Support Hypothesis

This graph shows a close degree of correlation, with a couple of points outstanding. This means that the prices of the red cars are generally low, so far supporting my hypothesis. Also, by looking at the graph I have discovered that the average price is approximately £2500; I know this because most of the points are gathered around this figure, and my line of best fit (hand drawn) supports this.

This graph shows that the price of the silver cars in general is higher then that of the red cars. The majority of the points are gathered around the £7000 mark. The graph starts of with a negative correlation but ends with a positive one.

This graph of Blue used cars shows that the prices of these cars are generally high, but not as high as the silver data. The line of best fit shows that the majority of the points are gathered around the £4500 mark, even though there are a few outstanding points that are below £2000.

So far, I have found these graphs helpful, but not as accurate as I had planned, so now I am going to complete the investigation into the hypothesis by using a different method, a Box Plot (box and whisker diagram). It will give me a more accurate reading as all 3 data sets will be one the same graph, so therefore it will be easier to analyse and compare.

I did this box plot by using the Autograph computer software. I think this is a very clear method to use, as it is colour co-ordinated (to the relevant car colour) and bolder than the scatter diagrams.

This chart will display my findings from the box plot:

LQ = Lower Quartile / UQ = Upper Quartile (I have rounded up the figures to the nearest ten to make the information easier to interpret)

This information shows that the Blue cars have the highest ‘Lower Quartile’ figure, but the Silver car data has the highest median and ‘Upper Quartile’ figure. The inter quartile range figures also support the fact that silver cars are more common than blue and red because it has the highest figure, followed by blue, and then lastly, red.

Conclusion for Hypothesis 1

Relating back to the beginning of this investigation, I have found that my hypothesis “The price of a silver used car will be higher then that of red and blue used cars” is correct. After investigating this by using scatter graphs and box plots I found that the results not only supported this, but strongly supported it. I now know that colour is a very important factor in the sale of a used car, and silver is the most common and expensive car colour above red and blue.