Question
Is it possible to get any more detail on the actual algorithm that is run on the main PCCF file to produce the best match in addition to the wording below?From the codebook we have:
" The single link indicator (SLI) was created to assist users in dealing with postal codesOM with multiple records. The method used to establish the single link indicator identifies the geographic area with the majority of dwellings assigned to a particular postal codeOM"
Answer
It looks like you are looking for Postal CodeOM Conversion File (PCCF), Reference Guide, June 2013 <http://www.statcan.gc.ca/pub/92-154-g/92-154-g2013001-eng.pdf>. This is only part of the explanation for Single Link Indicator (SLI) available in the guide. Further on in the guide, there is an explanatory note regarding using the SLI for retrieving distinct records, in section 4 (Technical specifications, Record layouts and data descriptions: <http://www.statcan.gc.ca/pub/92-154-g/2013001/tech-eng.htm>
Single link indicator (SLI)
The single link indicator (SLI) provides a geographic record for mapping a postal codeOM representative point. It can be used to establish a one-to-one relationship between postal codesOM and dissemination areas, dissemination blocks, or block-faces. The SLI has the value of '1' to flag one record of an active postal codeOM. Every set of retired records for a postal codeOM, for a given retirement date, has one SLI equal to '1.' The SLI value '0' indicates additional records.
For more information as to how the link was established, refer to section 5. (Data Quality, Lineage, Linking to 2011 Census geographic areas: <http://www.statcan.gc.ca/pub/92-154-g/2013001/qual-eng.htm>
Many postal codesOM are represented by multiple records on the PCCF.The single link indicator (SLI) is created to assist users dealing with postal codesOM having multiple records. The SLI provides a geographic record for mapping a postal codeOM representative point. The SLI has a value of '1' to flag the best (or only) link for a given postal codeOM. The value '0' indicates an additional record. Please note that the SLI is identified on both active and retired postal codesOM. Users will find when working with both active and retired postal codesOM that multiple SLIs will appear for a postal codeOM that was retired and reintroduced. However, there will only be one SLI for a set of active records for a postal codeOM. When assigning the SLI, priority is given to postal codesOM associated with civic addresses or dwellings (based on the PCtype). The confidence of coding to the geographic area (the quality indicator) and the precision of the geocoding (the block-face, dissemination area or dissemination block), as well as the population, are considered. When the postal codeOM was linked to a DA associated with multiple federal electoral district (FED), population centre (POPCTR), or designated place (DPL), the SLI is linked to the record represented by the greatest proportion of the FED, POPCTR, or DPL population.
Users are cautioned that the SLI provides only a partial correspondence between the postal codeOM and other geographic areas.
