Experts address census worries

Published Nov 2, 2012

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Ethel Hazelhurst

Dissident views on the quality of Census 2011 had not been ignored, South Africa’s statistical authorities said yesterday.

Howard Gabriels, the chairman of the Statistics Council, called an urgent press conference in Johannesburg to respond to census critics.

Doubts have been raised about the validity of the findings, released on Tuesday.

And demographers at the UCT Centre for Actuarial Science, Rob Dorrington and Tom Moultrie, described the final stages as rushed.

The researchers are independent experts who assisted with the process and expressed concern about apparent anomalies in the data. Gabriels said the council had taken the views of Dorrington and Moultrie “very, very seriously”.

He recounted that, on the third day of the council’s deliberations on the census findings, when he learnt of the reservations of Dorrington and Moultrie, he had stopped the meeting and asked each council member whether to advise the minister to hold back the results of the census.

He said all had agreed that the census was “fit for use” and that the minister should release the findings. He described council members as “respected statisticians, social scientists and economists”.

He said originally Planning Minister Trevor Manuel had set October 10 as the date for the release of the census.

“Having received the reports from Moultrie and Dorrington, we approached the minister to delay by a few weeks and the minister agreed, which gave us an additional three weeks to work on the data,” Gabriels said.

He pointed out: “As chair of the council, if I believed there were fundamental flaws in the census results, then I would not be doing my duty as required by law to advise the minister. And I take that personally.

“And I am sure every council member takes that weighty decision personally.”

Dorrington commented yesterday: “There was no discussion with us of the concerns raised in our report.”

Statistician-general Pali Lehohla argued at the press conference that no census provided perfect results and the margin of error in the census was in line with international norms and UN standards.

Gabriels brought in a panel of experts to address some of the concerns.

Among them was Griffith Feeney, a demographic consultant assisting Statistics SA.

Feeny said that, among the points raised by critics, was the age distribution. The data showed a bigger-than-expected bulge in the younger age groups, which implied a recent rise in fertility.

“Professor Dorrington pointed out a pattern in the age distribution that seemed very peculiar and unexpected. And we were suspicious that it was due to an error of some kind.”

But, “after intensive work with StatsSA staff”, Feeny found confirmation from other data sources.

These included age distribution data from Census 2001, birth and mortality data.

And he said these three largely independent statistical sources confirmed the trend in the latest findings.

He described the pattern in the age distribution as “real” but admitted: “It’s surprising, it’s unexpected.”

Gabriels said it would be up to “the scientists to investigate” the reversal in the previous declining trend.

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