Australian Bureau of Statistics

Rate the ABS website
ABS Home > Statistics > By Catalogue Number
ABS @ Facebook ABS @ Twitter ABS RSS ABS Email notification service
2940.0 - Census of Population and Housing - Details of Undercount, 2011  
Latest ISSUE Released at 11:30 AM (CANBERRA TIME) 21/06/2012   
   Page tools: Print Print Page Print all pages in this productPrint All RSS Feed RSS Bookmark and Share Search this Product

COMPONENTS OF NET UNDERCOUNT


COMPONENTS OF NET UNDERCOUNT

While net undercount estimates measure Census coverage, and adjustment factors are a means of adjusting Census counts for coverage, it is also important to understand the contributing components of net undercount.

The components of net undercount for a category are:

  • undercount (the number of people in that category who were missed in the Census);
  • overcount (the number of people in that category counted in the Census when they should not have been);
  • differences in classification between the PES and Census (for example, where age, sex or Indigenous status information does not match); and
  • imputation error (either under or over-imputation) in the Census.

This section provides additional information on these components to assist in the interpretation of estimates of net undercount presented in this publication.


Contact and non-contact sector

Table 13 provides estimates of the key components of net undercount, the definitions of which follow the table. For the purposes of PES estimation, Census dwellings deemed occupied on Census night are divided into a 'contact' sector (dwellings for which a Census form was received before the commencement of PES enumeration) and a 'non-contact' sector (where no Census form was received or a Census form was received after the commencement of PES enumeration - that is, a 'late return').

13 COMPONENTS OF NET UNDERCOUNT(a)(b), Contact and non-contact sector - 2011

UNDERCOUNT IN THE CONTACT SECTOR
Persons missed in
the Census
Net difference in
classification
Persons with Census
category not-stated
Total undercount in the contact sector
Undercount in non-contact sector
Net undercount
no.
no.
no.
no.
SE
no.
SE
no.
SE

Australia
634 579
-
-
634 579
25 380
-260 039
27 611
374 540
38 315
State/territory of usual residence
New South Wales
217 639
4 651
-
222 290
18 507
-85 644
18 012
136 647
26 865
Victoria
120 917
-5 098
-
115 819
11 283
-58 912
13 630
56 906
17 864
Queensland
139 820
-3 269
-
136 550
11 612
-59 336
12 466
77 215
17 431
South Australia
32 446
-803
-
31 644
4 727
-14 361
4 344
17 283
6 045
Western Australia
87 034
2 211
-
89 246
7 760
-31 327
8 800
57 918
12 004
Tasmania
13 839
1 041
-
14 880
2 369
-4 619
1 709
10 261
3 076
Northern Territory
16 609
1 952
-
18 561
2 642
-2 845
1 402
15 716
3 074
Australian Capital Territory
6 274
-685
-
5 589
2 209
-2 994
2 027
2 595
3 055
Sex
Male
393 555
1 664
-
395 219
17 603
-154 423
16 281
240 796
24 534
Female
241 023
-1 664
-
239 360
14 827
-105 615
14 508
133 744
20 772
Age groups (years)
0-4
49 140
-22 080
-
27 060
6 344
-9 797
4 772
17 263
8 017
5-9
29 582
-586
-
28 996
6 680
-9 069
4 118
19 926
7 781
10-14
19 312
729
-
20 042
6 511
-14 127
3 761
5 914
7 664
15-19
46 229
-2 473
-
43 756
7 534
-7 861
4 865
35 895
9 044
20-24
108 284
7 686
-
115 970
10 635
-7 821
6 638
108 148
12 812
25-29
95 330
-188
-
95 142
10 487
-2 505
7 812
92 636
13 444
30-34
59 418
3 548
-
62 966
8 415
-18 019
5 450
44 946
10 407
35-39
49 768
-15 574
-
34 194
7 650
-16 987
4 897
17 207
9 424
40-44
37 122
5 794
-
42 915
7 644
-21 892
4 100
21 023
8 856
45-49
37 607
-6 756
-
30 851
7 013
-25 360
3 687
5 491
8 063
50-54
30 646
7 866
-
38 513
7 131
-24 765
4 242
13 747
8 411
55+
72 142
22 032
-
94 174
9 610
-101 834
7 172
-7 659
11 500
Registered marital status
Never married(c)
425 154
34 811
-
459 966
22 591
-74 371
18 606
385 595
29 990
Widowed, divorced or separated
74 578
-66 701
-
7 877
12 757
-32 148
6 714
-24 271
14 630
Married
134 847
31 889
-
166 736
15 225
-153 520
10 761
13 216
18 737
Indigenous status(d)
Indigenous
56 650
5 128
7 009
68 787
11 982
45 402
5 969
114 188
14 274
Non-Indigenous
577 928
-5 128
280 012
852 812
25 388
465 987
26 476
1 318 799
37 272
Country of birth(d)
Australia
405 053
14 448
307 088
726 589
20 883
335 809
20 578
1 062 398
30 156
England
21 653
-15 325
22 106
28 434
6 270
15 761
3 082
44 195
7 049
New Zealand
23 881
-3 398
8 368
28 851
4 894
17 685
3 766
46 536
6 344
China
33 905
-4 261
6 002
35 646
6 782
20 319
5 062
55 965
8 934
India
12 117
-2 246
5 336
15 207
3 829
16 487
4 811
31 694
6 075
Italy
2 904
-2 248
6 775
7 431
2 169
1 453
1 067
8 884
2 513
Vietnam
9 389
-1 765
4 458
12 082
4 075
4 013
1 984
16 095
4 313
Philippines
6 090
3 171
3 318
12 579
3 053
4 527
1 884
17 106
3 603
South Africa
3 496
-895
2 289
4 890
2 013
6 822
2 755
11 712
3 383
Scotland
1 268
-7 096
3 506
-2 322
1 733
3 904
1 374
1 582
2 208
Other overseas
114 821
19 616
53 599
188 036
12 411
85 768
9 553
273 804
15 894

- nil or rounded to zero (including null cells)
(a) Estimates are based on a sample survey, and hence are subject to sampling error indicated by the SEs provided. For further information see the Sampling Error Technical Note (in Explanatory Notes).
(b) A negative value indicates a net overcount.
(c) Includes those who are living with a de facto partner and have never been in a registered marriage.
(d) Net undercount is based on Census counts for a category. In the Census, Indigenous status and Country of birth were set to not-stated where the response was blank and where imputed person records were created for non-responding dwellings. Hence components of undercount for Indigenous status and Country of birth do not sum to the Australia total.


Persons missed in the Census in the contact sector

For a given category of person as reported in the PES (e.g. 'Males' recorded in the PES), 'Persons not counted in the contact sector' is the difference between the number of people in that category that should have been counted in the Census and the number of people in that (PES) category that were counted on Census forms (irrespective of their Census category).

Net difference in classification in the contact sector

Occasionally, the responses obtained for a person in the PES interview are not consistent with those obtained for the same questions in the Census. In addition, where a value has been imputed in the Census for a missing response (for example, Age, Sex, or State/territory of usual residence), it may differ from the PES response.

The net difference in classification for persons actually counted in the Census contact sector is equal to the estimated number of people in the given category as reported in PES, minus the number counted in that same category in the Census. For more information see the Differences in classification Technical Note (in Explanatory Notes).

Persons (in the contact sector) with Census category not-stated

The Census contact sector contains some dwellings which were responding in the Census but returned only a partially completed Census form. For Census purposes, values for Age, Sex, State/territory of usual residence and Marital status are imputed during Census processing in cases where these items have been left blank. Missing values for other items remain 'not-stated' in the final version of Census counts (including Indigenous status and Country of birth). Persons in the contact sector with a Census category value of 'not-stated' contribute to net undercount estimates for the category in which they should have been counted as reported in the PES (e.g. Indigenous status).

Undercount in the non-contact sector

Non-responding dwellings in the Census are dwellings where the Census never obtained a return, and the dwelling could not be established as having been unoccupied on Census night. During Census processing, a 'hot-deck' imputation method (see Glossary) was utilised to impute people and their Age, Sex, Marital status and Place of usual residence into these dwellings. These values were, in many cases, based on information provided by the Census collector about the dwelling and its residents. Values for all other variables (e.g. Indigenous status) were set to 'not-stated' or 'not applicable', depending on the imputed value for Age.

Inevitably, the imputed values differ from the true but unknown values.

Imputed records made up the majority of the 2011 Census non-contact sector. Late returns made up only a small proportion of this sector.

An estimate of the undercount in the non-contact sector for a category of person is obtained by calculating the difference between the PES estimate of the number of people who should have been counted in the non-contact sector in that category (as reported in the PES) and the Census count of people in the non-contact sector for the category (including imputed person records within the category). For a category of persons classified by Age, Sex, Marital status and State/territory of usual residence, this component of net undercount largely represents an estimate of imputation error in the Census for this category of imputed persons. For the Indigenous status and Country of birth categories, this component largely represents an estimate of persons who should have been counted in this category in non-responding dwellings.


Bookmark and Share. Opens in a new window

Commonwealth of Australia 2014

Unless otherwise noted, content on this website is licensed under a Creative Commons Attribution 2.5 Australia Licence together with any terms, conditions and exclusions as set out in the website Copyright notice. For permission to do anything beyond the scope of this licence and copyright terms contact us.