The Australian Bureau of Statistics has revealed that its own gloating about census completion rates cannot be trusted.

The ABS has claimed all that concern about privacy and the website debacle was for nothing, with close to 95% of households completing their forms by last week’s deadline.

But in its submission to the Senate inquiry — which was posted and then removed when a committee officer failed to remove confidential information from the submission — the ABS expressly states that final participation rates in the census would be finalised at the end of the collection phase and that “final dwelling response rate is not known at this time”.

The actual response rate will not be known until early 2017, after processing. A total of 6743 people have flat-out refused to complete the census as of September 20, 2016. About 460,000 households have not yet completed the form, but they have not notified the bureau that they are refusing on principle.

[Panicked ABS top dogs declare census return ‘crisis’]

The ABS also revealed how it planned to link the data over time. The ABS said it would be “creating anonymised linkage keys on a project-by-project basis”.

One of the major criticisms of the decision to keep names and addresses was that the ABS’ privacy impact assessment was an internal assessment, not conducted by an independent third party, as recommended by the Privacy Commissioner. The ABS responded by saying that there was “no requirement” for an independent privacy impact assessment.

As Crikey‘s political editor Bernard Keane notes elsewhere today, the ABS throws IBM under the bus several times in the submission because of the failure of the online census form. In 2012 the ABS examined whether the existing platform for the previous census would be appropriate for the “digital first” approach encouraging people to fill out their census online rather than on paper. It wasn’t until 2014 it was decided that a new platform was needed, and due to the limited time available, the ABS decided to issue a “limited tender” to IBM given IBM’s experience in this area.

[The census cannot force you to give your name]

The timeline provided in the submission of the events of September 9 that brought down the online census form contradict the statements made by Small Business Minister Michael McCormack at the time. McCormack said the ABS had made the decision to shut down the form at 7.45pm, but the ABS says in its submission that IBM attempted to reboot the system at 7.43pm after a distributed denial of service attack at 7.45pm, and it wasn’t until after 8pm that the ABS asked IBM to prevent people filing new census forms.

McCormack also said that the system had been restored at 8.50pm but overload controls kept people from filing forms after that point, but the ABS submission makes no reference to this, stating that at 10.26pm IBM was finally able to reboot the system but it was kept offline to resolve the security concerns held by the ABS.

Amusingly, the ABS notes that while the system was offline, the ABS census Twitter account kept telling people to complete their census forms, and that Twitter “was still attempting” to turn off the automatic retweet subscription as late as 9.20pm on the night of the census debacle.

In the fallout from the online census failure and the ongoing privacy concerns around the handling of names and addresses, the ABS told the committee it would establish an “independent panel” to review the census and would “work proactively with key users and the public ore broadly to ensure that there is a sound understanding of the quality of the Census results”, when the first release of data happens in April next year.