StatsCan didn't pre-test troublesome census web page

Thousands of Canadians trying to file their census information online were cut off on May 2 because of website problems. Statistics Canada acknowledges it did not pre-test the image-rich webpage that led to severe congestion.

Lack of testing was behind census website congestion problems, Statistics Canada confirms

Statistics Canada has acknowledged it did not pre-test a key census webpage that led to severe congestion problems on May 2, when thousands of Canadians were prevented from filing their data online. (Canadian Press/Sean Kilpatrick)

Statistics Canada failed to pre-test a troublesome web page that gummed up its online census system last month, CBC News has learned.

The so-called "landing page" — the first web page Canadians saw when they tried to file their 2016 census information — was far too big for the expected volume of traffic on May 2.

The page contained too many large images, and downloading them to home computers clogged up the system, preventing thousands of Canadians from filing their census information that evening.

Statistics Canada says its census website has been down for only 94 minutes since May 2. (Statistics Canada)

The congestion surprised technicians because at the time there were only about half the maximum number of users the website was designed to handle.

It soon became apparent the landing page was too large because of nine images that had been added to it the day before, on May 1.

The page, rich in visuals, was never tested to see whether it could withstand the busy traffic expected May 2, the first day Canadians could go online to file their 2016 census data.

Technicians scrambled to compress the images, and thereby reduce the size of the landing page, before normal service was restored.

The "landing page with images was finalized on May 1 and deployed," Marie-Claude Deslandes of Statistics Canada said in an email.

Too big for bandwidth

"During the testing phase conducted prior to deployment, the landing page did not include images. Once the page was deployed with images, it was deemed to be too big for the available bandwidth."

CBC News has obtained internal documents identifying at least two flaws in the agency's online census system that were not caught by pre-tests and which led to technical problems on May 2.

The website had to be shut down temporarily that evening. Statistics Canada suggested at the time that Canadians' "enthusiasm" for filing their census data simply overwhelmed the system.

The agency posted a public notice on the census website saying it was down for "scheduled maintenance," which a spokesman now says was incorrect and the result of human error.

William Garland also said the landing page without images was pre-tested for "usability and for display on mobile devices," but was not tested for high traffic — or what's called "volume testing" — because it was incomplete without those images.

During the testing phase conducted prior to deployment, the landing page did not include images.- StatsCan spokeswoman

"It was not included in volume testing … because final content for the landing page was not ready at the time of volume testing," he said.

The internal documents, obtained under the Access to Information Act, also show that testing did not uncover a flaw in another part of the system that forced a shutdown at 8:45 p.m. ET for about a half hour.

"Statistics Canada always volume tests as many scenarios as possible before applications are put into production mode," Deslandes said. "However, not all scenarios can be predicted."

Statistics Canada says the system was unavailable to Canadians that night for 45 minutes, although the documents indicate technical problems persisted for almost three hours.

3rd problem blacked out

A third problem hit the system, but all details are blacked out in the released material ostensibly to safeguard sensitive information about computer security.

The agency says a maximum of 26,000 users were denied access to the website, and that all the technical problems were cleared up late on May 2. The internal documents, however, refer to "several million" Canadians affected.

Letters from Statistics Canada containing access codes for the 2016 census ask recipients to complete it by May 10. In the first 52 days, some 13 million completed census forms have been received. (Alistair Steele/CBC)
Statistics Canada says it has received about 13 million census responses after 52 days.

"Since May 2, we have been down for maintenance or to correct minor issues for only 94 minutes out of 74,880 minutes, so the applications were available 99.75 per cent of the time," said Deslandes.

Some 15 million households were sent census notices through Canada Post in early May, with most receiving a 16-digit access code rather than a questionnaire to encourage them to file online.

The budget for the 2016 census was about $715 million spread over seven years.

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About the Author

Dean Beeby

Senior reporter, Parliamentary Bureau

Dean Beeby is a CBC journalist, author and specialist in freedom-of-information laws. Follow him on Twitter: @DeanBeeby