Critique of CensusLiving between the linesNotesObservations

A Quantitative Methods Professional Answers Us…

Débats - DebatesThis is a response to previous post from a professional who wrote me, but do not wish to be identified for the moment:

Quantitative methods professional

The idea that a volunteer sample reduces the reliability and the validity of data is today as accepted an idea than the one that the earth is round. […] There are many articles that deal with the extent of the bias, its reasons, the ways that can be used to circumvent these biases somehow, etc. But one can never really succeed to circumvent them.

[As for Justice Boivin’s finding] I have not read the arguments in favour of a voluntary survey and how they think they can avoid the sample biases. Of course there is uncertainty about the reliability of data from the NHS, since we have never done this exercise before. There is one certainty about the fact that the data will be biased, but it is difficult to predict in advance the extent and nature of this bias.

Increasing the number of long questionnaires will not change the bias, and nothing leads us to believe that an advertising campaign can correct the bias. The campaign could very well increase it (especially if only in the two official languages). (more…)

Critique of CensusDebatesLiving between the linesNotesObservations

Questions for Statisticians and Specialists in Quantitative Methods regarding the Reliability of a Voluntary Census

In the wake of the decision on a application for judicial review form the Fédération des communautés francophones et acadienne du Canada

ObservationsFederal Court’s Justice Richard Boivin heard evidence and testimonies presented in support of and in opposition to the National Household Survey (NHS) which, being voluntary, replaces the old census long form, which was mandatory under fine and even imprisonment. The judge ruled this week that “there is uncertainty about the reliability of the data that will come from the NHS” … except that the Court is “not convinced that the data of the NHS will be so unreliable as to be unusable.”

Let’s recall that the Conservative government decided to remove the long form from the mandatory status of the Canadian census to make it voluntary instead. To offset a possible decline in participation, it provided an increase of around 50% of the number of long questionnaires (from 3 to 4.5 million households at an additional cost of $ 30 million) plus an advertising campaign to spur participation.

Many statisticians, demographers and researchers have criticized this decision. According to them, a voluntary survey would lead to a significant decrease in participation, particularly in certain portions of the population (the poorest, the least educated, of certain ethnic backgrounds). The result would be less representative and thus biased data which would distort the demographic profiles of country, regions and local communities. However, beyond these general statements, public interventions in the media so far have provided no statistical demonstration in support to this claim. Justice Boivin’s finding seems to confirm this perception.

So I make an appeal to statisticians and specialists in quantitative methods in order to clarify certain key elements of the debate. (more…)

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