Five years ago, Canadian Prime Minister Stephen Harper made participation in Canada's constitutionally mandated long-form census voluntary.

The consequences of not requiring people to fill out the country's National Household Survey are becoming increasingly clear, and they're not good: Canadian citizens, reporters, businesses and government officials don't know how the country is changing. Fewer people respond to voluntary censuses, leading to spotty demographic data . As economics writer Ben Casselman reported at FiveThirtyEight.com , nearly three quarters of the residents of Snow Lake, Manitoba, didn't return the census form at all.

That pattern is holding in hundreds of small communities across Canada. Statistics Canada, the government agency that administers the census, tried to fix the problem by sending the voluntary form to 1 in 3 households instead of 1 in 5. But response rates fell anyway, from 93.8 percent in 2006 to below 70 percent in 2011.

Wayne R. Smith, the chief statistician of Canada, acknowledged in a blog post on June 4 that the shift has had an impact on response rates and, in some cases, data quality:

Statistics Canada has always stated that a mandatory survey will inevitably produce data of better overall quality than a voluntary survey of the same size, all other things being equal. The 2011 National Household Survey achieved a collection response rate of 68.6% and a weighted response rate of 77.2%significantly lower than the 2006 Census long form that achieved a response rate of 93.8%.

To offset the data quality risks associated with the move to a voluntary survey, the agency took many measures to reduce risks, and invested a great deal of effort in assessing and reporting on the quality of the resulting estimates. Where Statistics Canada deemed that estimates were not of sufficient quality (or not fit for use), it did not release them; where we deemed the estimates were to be used with caution, we communicated this to users. The remaining estimatesthe vast majoritywere deemed fit for use, and released without caveats. Based on this work, we can say that the National Household Survey produced a rich and robust database of information.

Canada has been conducting a national census since 1871 , and started sending out a long-form census in 1971. The short-form census poses 10 basic questions about the composition of households, including the number of people present, their age, sex, marital status and languages spoken.The long-form census -- the National Household Survey -- poses 53 more questions about demographics, activities, socio-cultural information, mobility, education, labor market activities, income, housing, childcare and household work, occupation and industry.

In the absence of this much richer data set, businesses know less about where to offer services , what to invest in or where to locate new stores, and they're not happy about the impact this lack of information is having on their competitiveness . Academic researchers have less insight into what's happening with immigration, public health and poverty. Government agencies can't measure the efficacy of their programs . And journalists can't cover the communities they serve as effectively; for example, stories like this WBEZ piece on Chicago simply aren't possible.

When I traveled to Ottawa this year for the International Open Data Conference, I asked Parliament member Tony Clement, the president of Canada's Treasury Board, about this issue. Clement is the Harper administration's lead on open government -- an issue that's relevant to a broad range of organizations .

Open census data has economic and social value; a lack of quality data damages both economic and social interests. (Disclosure: I have been an unpaid, voluntary member of the Canadian government's Advisory Panel On Open Government since it was formed in 2012, and I've raised concerns about transparency, participation and access to information at every annual meeting since.) Video from the 3rd International Open Data Conference can be viewed below:

At minute 33 , I asked Clement about whether he would urge Parliament to reconsider Canada's discontinuation of the mandatory long-form census.

"We're at a stage where we can move beyond the old way of collecting information, and we have the tools to do so," Clement replied. "We can do so in a way that preserves privacy, we can go deeper than any long-form census can go."

Clement also expressed concern about the civil liberties implications of personal data collection, echoing Harper's justifications for eliminating the mandatory aspect of the long-form census.

He challenged the public to "find a new way to get the information we need that respects privacy and those that are concerned about the intrusion of the state."

While Clement implied the technology to collect "better, more accurate, deeper information" was available now, he offered no substantive plan or method that would replace a mandatory household survey.

Adopting new technology for the census could also raise new issues. Using websites or mobile devices for explicit or tacit data collection, for instance, could be more invasive with respect to privacy and civil liberties. There's also a risk of a bias towards counting people who are connected versus those who are not. Internet access in Canada varies by province, ranging from 78 to 86 percent of the population. And only 62 percent of those in Canada's lowest income quartile have Internet access, which could leave the country's poorest off the books if the country adopted an all-digital survey.

Meanwhile, although hundreds of organizations and individual scientists and researchers have called for it, in June 2015 the Harper administration declined to add more questions to the next version of Canada's short-form census -- meaning the phenomenon author Stephen Marche referred to as "The Closing of the Canadian Mind " in a recent opinion piece for The New York Times isn't likely to reverse in 2016.

Whether Canadian voters decide this should be a crucial issue in the country's upcoming general election is, like so many other things about Canada these days, unknown. Justin Trudeau, the leader of Canada's Liberal Party , has said that he'll bring the mandatory long-form census back if he becomes prime minister. Trudeau has been paying attention to the issue since 2010.

At present, the cost of living, food prices, pensions, the economy and the environment are the issues Canadians care about most , according to a July 2015 Ipsos poll. If politicians and media clearly tie the absence of good data to those issues, maybe Canada's citizens will see the country's census choices as relevant to the pocketbook issues they vote on.

CORRECTION: An earlier version of this article misidentified the leader of the Liberal Party of Canada as Pierre Trudeau. The party leader is in fact Justin Trudeau. The story has also been corrected to clarify that Canada began its census in 1871, and began sending out a long-form version in 1971.