Data Issues

Waves 1 to 7
Data issues - Waves 1 to 7 – February 2019

22 Executive functioning - CogState - missing data Wave 7

The executive functioning of children in the K cohort was tested at Wave 6 using three Cogstate cognitive tests, including the Identification task (IDNT), One-back test (ONBT), and Groton Maze Learning Test (GML). In Wave 7, the same battery of tests was used to examine the executive functioning of the P1 of K cohort children. The outcome variables are contained in the CogState dataset, where a series of cognitive testing batteries have been customised for use in LSAC. Each row of a CogState dataset represents one task in the CogState test battery for one study subject in one test session. Further information is available in the Data User Guide, Wave 7 , and the LSAC Technical Paper No. 19, Executive Functioning – Use of Cogstate measures in the Longitudinal Study of Australian Children [PDF, 401 KB]

At Wave 7, 465 parents (15% of Wave 7 responding sample) had missing CogState data. Reasons for parents’ CogState data being missing are presented in Table 39.

Table 39: CogState interviews for the K cohort in Wave 7
  Number Percentage
Not in scope
SC only interviews (RAP) * 13 0.4
SC only interviews (Non - RAP) * 15 0.5
7.25 interviews * 13 0.4
In scope
1. CogState data present 2,624 84.9
2. CogState data not present - no consent given * 312 10.1
3. CogState data not present - module could not be completed due to systems issues * 32 1.0
4. CogState data not present - data loss due to systems issues * 61 2.0
5. CogState data not present - consented but did not complete any tasks * 10 0.3
6. CogState data not present - partially responding record, didn't get to exec. module * 9 0.3
Total interviews for K cohort in Wave 7 3,089 100.0

Note: *Sum of 465 interviews.

The most common reason for missing CogState data was no P1 consent. The level of consent was lower among parents (89.1% of responding Wave 7 sample) than study children (99.5% of responding Wave 6 sample).

Table 40: CogState data not present - breakdown of reasons for consent not given
Reasons Number Percentage
Time constraints 99 31.7
Don’t want to do a test/puzzle 83 26.6
Computer literacy 24 7.7
Tired 23 7.4
No reason 20 6.4
Illness/injury 19 6.1
Telephone interview 18 5.8
Environment Issues 12 3.8
Language 8 2.6
Technical difficulties 6 1.9
Total 312 100.0

During Wave 7 enumeration, executive functioning files were obtained and loaded monthly to speed up processing and also to ensure the software and ABS systems were working properly. Through this early processing, the ABS discovered two issues accounting for records in categories 3 and 4 in Table 39.

22.1 Category 3: CogState data not present - module could not be completed due to systems issues

The module could not be completed for two main reasons: (1) one interviewer had not had CogState software installed on the laptop (accounting for 11 missing records); and (2) the software kept crashing at the time of testing (accounting for the rest of records).

22.2 Category 4: CogState data not present - data loss due to systems issues

Some records had missing executive functioning files (encrypted files containing the executive functioning data) even though it appeared that the CogState software had run successfully. The common pattern for affected records was a combination of a male Parent 1 and a female study child. In these circumstances, incorrect instrument coding caused the sex of the person completing the tasks to be missing. This resulted in the executive functioning file not being created.

Once this issue was uncovered during the enumeration process, interviewers were instructed to change the sex of P1 to female for any remaining records that had a combination of male P1 and female SC. This enabled the executive functioning module to work and processing staff subsequently changed the sex of P1 back to male. There were 78 Wave 7 interviews that were affected by this issue. Of these:

  • Thirteen did not consent to complete the executive functioning tasks.
  • Thirteen successfully had the sex of P1 changed by the interviewer to female to allow the executive functioning module to work.
  • Fifty records did not get the sex changed and therefore there is no executive functioning data.
  • Two did not work for other reasons (category 3, system crash or software missing).

In addition, there were 11 records where the P1 sex was changed from female to male due to a role change in the household or because the sex was incorrect. This also resulted in data loss.