Polk Data Collection and Methodology
The Polk New Registrations and Polk Used Registrations datasets are fact-based, meaning they contain records for U.S. vehicle registrations. Information is gathered from the following sources:
- Individual states
- Vehicle manufacturers
- Finance companies
- Third-party sources
However, the amount of information varies between new and used registrations:
- New Registrations: All new registrations are recorded for all vehicles in all states, down to the ZIP Code level. However, some manufacturers and some states don't report dealer-level information.
- Used Registrations: It's more difficult to collect data for used registrations, in part because selling a used car is often a private transaction. For those states who report used registrations, the information comes from the updated registration and title (a change in the last name and address associated with the original registration), or from those car manufacturers who run certified pre-owned programs.
In addition, not all states and not all car manufacturers report the same level of information.
- Participating states, which are green on the map below, receive selling dealer data from the state. All vehicle manufacturers are represented for both New Registration and Used Registration datatsets because the information comes from the state's title record.
- Non-participating states, which are red on the map, do not receive selling dealer data from the state. Only participating vehicle manufacturers are represented for the New Registrations dataset. No dealer information is available for the Used Registrations dataset.
- Participating makes: The manufacturers report sales and registration data for new and used vehicles. Dealer data is reported for new registrations, but not for used registrations.
- Non-participating makes: These manufacturers do not report sales and registration data.
Figure 19: The IHS Polk Selling Dealer Data Availability map, provided by IHS Polk (click to enlarge)
It can be difficult to parse this map; if you want to download a full version of it, you can do so here: http://bit.ly/1Wifg7y).
There are a few anomalies on the list.
|CA / WA / VA||Dealers selling vehicles through a branch location will have those vehicles reported at their headquarters/parent location. This happens because there is no "Branch" indicator on the state's title record, which contains the same base code for both a branch and a headquarters/parent location.|
|TX / IA / ND||These states provide only a selling dealer name and address on the title record, but no code. Misspellings in the name or address cause matching inefficiencies when trying to match the dealer name to Polk's National Dealer Census file (used to report a standardized name of a dealer).|
CT / ID/ OH /
SC / CO
|Because of the timing between the release of the registration data and the title data, the selling dealer coverage will be lower in the initial month of reporting. The coverage will improve in the subsequent month of reporting.|
|WV||Polk last received a dealer roster from West Virginia in 2002. The state has changed its policy on releasing its dealer roster (it no longer releases it). However, the state has continued to populate the dealer code on its title records. Dealer's codes that match the 2002 dealer roster are reported, but any newer dealers will not be reported.|
|LA||Louisiana has a higher-than-average "unknown" value for selling dealer counts (especially for non-participating makes). In addition, this state does not require dealer information on used transactions; therefore, selling dealer information in the Used Registration dataset will be extremely low.|
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