U.S. Bureau of Economic Analysis
Thousands of Units, Not Seasonally Adjusted
Motor vehicle sales: Heavy Weight Trucks indicates the number of drivers, number of vehicles, and vehicle supply and demand.
The data shows autocorrection, seasonality and a non-normal distribution. The data should be differenced and seasonally adjusted. While the Yeo Johnson transformation, provides the best normality, the Arcsin variable will also perform well.
Data is able to be distributed by time but not by geography. The roll up method used is Sum.
Heavy Weight Truck Retail Sales - Not Seas Adj
Auto Correction Function
Auto Correlation Function After Differencing
Partial Auto Correlation Function
Seasonal and Trend Decompostion
Data shows autocorrectation indicating a need for differencing
The ACF indicates 1 order differencing is appropriate.
Following first order differencing, no further differencing is required based on the differenced ACF at lag one of -0.54
The Kwiatkowski-Phillips-Schmidt-Shin (KPSS) test, KPSS Trend = 0.19 p-value = 0.02 indicates that the data is not stationary.
The Shapiro-Wilk test returned W = 0.97 with a p-value =0.02 indicating the data does not follow a normal distribution.
A skewness score of 0.34 indicates the data are fairly symmetrical.
Hartigan's dip test score of 0.03 with a p-value of 0.83 inidcates the data is unimodal
Statistics (Pearson P/ df, lower => more normal)
U.S. Bureau of Economic Analysis, Motor Vehicle Retail Sales: Heavy Weight Trucks [HTRUCKSNSA], retrieved from FRED, Federal Reserve Bank of St. Louis; https://fred.stlouisfed.org/series/HTRUCKSNSA, December 16, 2019.