Wednesday, April 17, 2019

PCCF: Population centre and rural area classification size; value =0

I did a quick search in the DLI listserv archive because I vaguely remembered seeing this question before, and indeed I found that the question was asked twice… but I could not find the answer to it on the listserv, so I will ask it again!

In the Population centre and rural area classification size  of the PCCF, why are there many records coded 0 . This does not correspond to a valid value listed in the documentation (from 1 to 4 depending on rural area or size of the population centre).

Here is an earlier answer from StatCan about this.  Please take a look to see if it answers your question?:

I have been provided with the following information from Subject Matter. As it is quite technical, I’ll be pasting it directly as I received it from them:
The PCCF starts by trying to link postal codes to block faces, but if it can’t it then moves up and tries to link them to DissBs, then DAs. The Rep_Pt_Type variable has the info on what level of link was made.

PopCentres are built from Dissemination Blocks (DissB), not Dissemination Areas (DA). See the hierarchy chart…

Thus, if the PCCF cannot link to a DissB for a particular postal code, and has to move up to the DA level, there is no way to link the postal code to a PopCentre. Many DAs overlap multiple PopCentres, so we can’t choose just one.

For the 125,163 records with a POP_CNTR_RA_SIZE_CLASS of 0, these all have a Rep_Pt_Type of 3, meaning they linked to a DA. So, there is no PopCentre data available for them.

That is the explanation for why the PCCF has 0 in the POP_CNTR_RA_SIZE_CLASS.

As the researcher is only looking at some of the records in the PCCF, depending on where these records (about 12,000) are, the possibility exists that the DAs they link to may or may not overlap PopCentres. With the Geographic Attribute File, we can create a correspondence between DAs and PopCentres, and test that correspondence with the researcher’s records.

If you wish to provide the researcher’s subset of PCCF records, we may be able to capture some useful PopCentre info. No promises, but this looks like a lead. Otherwise, the information provided by Subject Matter above is quite useful.