Transportation Deployment Casebook/2014/Sales of Hybrid Vehicles in the United States until 2012
The data collected for this study came from the Bureau of Transportation Statistics website, which was last updated until 2012. The data in the table showed number of hybrid vehicles that sold in united states since 1999 till 2012. Three parameters logistic function has been employed to analyze data.
S(t) = K/[1+exp(-b(t-t0)]
S(t) shows the status measure, K is saturation level, b is a coefficient explains the slope of the fitted curve, t is time (year) and t0 is the inflection point.
As data show about year 2007 the second deviation of the curve going to be zero. Data explain that in 2012 we are close to the mature point but it seems not true. Because hybrid vehicles can be more efficient and get better portion of the market. In this curve, the mature quantity of sales in US is about 433500 with R-square equal to 0.74. Recession in 2007 had a considerable impact on the sales and that can be a reason for the less quantity of maturity.