Trend Chart Notes

The trend charts are computed as follows:

Equipment type trend prices are calculated from the individual trends of the top ten models in the equipment type. Top models are determined based on how often they have appeared at auction over the last five years.
The equipment type trend prices are aggregated to create the industry trend prices.
If a model doesn't sell in a particular month, the last known auction price is repeated until the model sells at auction again. If a model doesn't have an auction price in the first charted month, the first auction price found is used from the beginning of the chart until an auction price is found.
Auction prices are standardized on model year by correcting values to look like a five year old model. If a new model is sold, its price is reduced by a factor of .75. Any model older than 10 years is increased by a factor of 2.5. In between, it's a smooth correction factor. A five year old model is not corrected since it's the standard.
If multiple units of a model are sold in the same month, all sales are averaged into a single data point.
Prices are smoothed using a 3 month running average.
No corrections are made for seasonal trends.