In an article on the 40¢ per gallon price reduction on gas, Chris Isidore claims that the average price of gasoline has decreased since its peak in April by 10%. This is an example of comparing two measures of central tendency without incorporating measures of position or dispersion. While the data gives a rough idea of how much the two numbers compare, it does not paint a picture of whether this 10% decrease is remarkable. It may be that the gas price commonly reaches 10% of the peak amount, or it may be that this has not happened for a long time. A better way to go about giving an accurate representation of the change in gas price would be to incorporate the average deviation from the highest value. First, the mean gas price from across the country would be computed for each day, or period of days. Then the mean gas price for each day would be divided by the mean for the peak day, or the day that the gas price was the highest. The resulting number would be the percentage of the highest value that every value represented. If other values often fell under 90% of the highest value, then the news would be unremarkable.
Although it is not included in the body of the article, there is also a graph demonstrating the fall in gas prices since April. This graph demonstrates a relatively steady decrease in gas prices since the beginning of April, from around $3.90 to $3.55. The downfall of this graph is that no precise values are given, preventing an accurate study of the specific data. It does demonstrate that the 10% decrease has been a gradual occurrence with few deviations, but it does not demonstrate how that 10% decrease compares to fluctuations in the value of gas prices in the past months and years. The question is whether or not the 10% decrease is part of a continuous pattern that would have been visible with more data, or if it truly is an unexpected change in gasoline’s value.
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- Isidore, C. (2012, June 15). Stimulus-by-the-gallon: Lower gas prices. CNN Money. Retrieved from http://money.cnn.com/2012/06/15/news/economy/gas-prices-stimulus/index.htm
