Thursday, February 21, 2019

Census 2016 PUMF Weights

A prof was delighted to be able to download the Census 2016 PUMF.

However, the weights do not seem to make sense to her.

These are her comments:
"I’m working with the PUMF file now and the weights look VERY odd. For starters, the file only contains 16 replicate weights – normally Stat Can provides 500 to 1000. For another thing, the individual (frequency weight) weight [variable name – WEIGHT] is nearly identical for all respondents.  Is that what Stat Can intended?
Any information you can pass on would be really helpful."

Subject matter has responded with the following:

“I’m happy to hear the prof is enjoying the PUMF.

We appreciate the concerns expressed by the user and we can assure them that the contents of the product are what Statistics Canada intended.

I would recommend that the users consult the PUMF user guide and codebook for answers to their questions. Chapter 3 – Sampling method, estimation and data quality should resolve any questions with regard to the Weight and replicate weight variables.”

Follow-up Question:
Here is the reply I received from my prof – and the answer provided by Subject division does not answer her question.

"Here’s an illustrative example where the application of the Weight variable creates some problems:

There are approximately 390,000 live births in Canada each year. When I run a cross tab to look at the number of women who are parents (couples or single parents) with a child under 1 year, I get a result of over 708,000, which just can’t be right."

I asked her for more detail to try to replicate how she got her answer and this is her reply:

"…my tabulation is restricted to women (Sex), of reproductive age (20 to 44 years per AGEGRP) who are in a couple with children or are single parents (CFSTAT) and who live with a child age 1 or younger  (PKID0_1).
Here’s my Stata output for the derived variable (as per above) “newmom”

. tabulate newmom [fweight = rndweight]

     newmom |      Freq.     Percent        Cum.
          1 |    708,291      100.00      100.00
      Total |    708,291      100.00"

Follow-up Answer:
I received the following response from subject matter:

“On page 109 of the 2016 Census Individuals PUMF User Guide, the PKID0_1 variable includes children aged 0 or 1. Therefore it provides data on presence of children as of Census Day and it includes children that are under the age of 2.

As a result, the counts of children in Census family here presents higher numbers. Foster children are not included in this grouping.”