8146.0 - Household Use of Information Technology, Australia, 2005-06

ARCHIVED ISSUE Released at 11:30 AM (CANBERRA TIME) 15/12/2006

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Explanatory Notes
Glossary
Abbreviations
Reliability of Estimates (Technical Note)
Data Source

TECHNICAL NOTE RELIABILITY OF ESTIMATES

RELIABILITY OF THE ESTIMATES

1 As the estimates in this publication are based on information obtained from a sample of households and persons, they are subject to sampling variability. That is, they may differ from the figures that would have been produced if all households and persons in Australia had been included in the survey. One measure of the likely difference is given by the standard error (SE), which indicates the extent to which an estimate might have varied by chance because only a sample of households and persons was included. There are about 2 chances in 3 that a sample estimate will differ by less than one SE from the figure that would have been obtained if all households and persons had been included in the survey, and about 19 chances in 20 that the difference will be less than two SEs.

2 Another measure of the likely difference is the relative standard error (RSE), which is obtained by expressing the SE as a percentage of the estimate.

3 In the tables in this publication, only estimates (numbers and percentages) with RSEs less than 25% are considered sufficiently reliable for most purposes. However, estimates with larger RSEs have been included and are annotated to indicate they are subject to higher SEs and should be used with caution. Estimates with RSEs of 10% to less than 25% are preceded by a ^, and estimates with RSEs of 25% to 50% are preceded by an asterix (*) to indicate that they should be used with caution. Estimates with RSEs greater than 50% are preceded by a double asterisk (**) to indicate that they are considered too unreliable for general use.

4 To assist readers of this publication to ascertain the approximate levels of reliability of estimates throughout this publication, tables of SEs and RSEs for certain estimates of population counts for the data appear at the end of this Technical Note. These values do not give a precise measure of the SEs or RSEs for a particular estimate but will provide an indication of their magnitude.

USING STANDARD ERRORS FOR POPULATION ESTIMATES

5 An example of the use of SEs in relation to estimates is as follows.

6 From table 4.1, it is estimated that 4,730,000 households accessed the Internet using a home computer in 2005-06. This estimate has a SE around 39,000. This means there are about two chances in three that the value that would have been obtained from a complete census is within the range 4,691,000 to 4,769,000 households and about 19 chances in 20 that the true value is in the range 4,652,000 to 4,808,000 households.

7 Particular care should be taken when comparing figures over time. It is not correct to assume that an apparent difference between figures is actually significant. Such an estimate is subject to sampling error. An approximate SE of the difference between two estimates (x-y) may be calculated by the following formula:

8 The estimated increase in the number of households with home internet access from the previous year was 337,000 (from 4,393,000 in 2004-05 to 4,730,000 in 2005-06). The SE on the movement is around 55,000. There are 2 chances in 3 that the true value is within the range 282,000 to 392,000 households and 19 chances in 20 that the true value is in the range 227,000 to 447,000 households.

9 Improved modelling techniques have resulted in some differences between SEs for states and territories in 2005-06 with those from 2004-05. The ABS considers 2005-06 estimates for SEs to be more accurate.

TABLES OF STANDARD ERRORS AND RELATIVE STANDARD ERRORS

Standard errors of household estimates-2005-06

		STANDARD ERROR								AUSTRALIA
		NSW	Vic.	Qld	SA	WA	Tas.	NT	ACT	Standard error	Relative standard error
		no.	no.	no.	no.	no.	no.	no.	no.	no.	%

Size of estimate
	100	140	180	160	110	140	120	130	120	180	180
	200	250	280	260	200	240	190	210	190	280	140
	300	330	370	340	270	310	240	280	240	360	120
	500	480	510	460	380	440	320	380	320	490	98
	700	610	620	570	480	550	390	460	390	600	86
	1,000	780	770	710	610	690	470	560	480	740	74
	1,500	1 020	980	900	780	870	580	680	580	930	62
	2,000	1 220	1 150	1 070	920	1 020	670	780	670	1 100	55
	2,500	1 400	1 300	1 200	1 050	1 150	750	850	750	1 250	50
	3,000	1 550	1 450	1 350	1 150	1 300	800	950	800	1 400	47
	3,500	1 700	1 550	1 450	1 250	1 400	900	1 000	850	1 500	43
	4,000	1 850	1 700	1 550	1 350	1 500	950	1 050	900	1 600	40
	5,000	2 100	1 900	1 750	1 500	1 650	1 050	1 150	1 000	1 850	37
	7,000	2 550	2 250	2 100	1 750	1 950	1 200	1 300	1 150	2 200	31
	10,000	3 050	2 700	2 500	2 050	2 300	1 350	1 450	1 300	2 650	27
	15,000	3 750	3 300	3 050	2 450	2 700	1 600	1 600	1 450	3 250	22
	20,000	4 350	3 750	3 500	2 750	3 050	1 750	1 700	1 600	3 800	19
	30,000	5 250	4 500	4 250	3 150	3 550	2 000	1 900	1 800	4 650	16
	40,000	5 950	5 100	4 800	3 500	3 950	2 200	1 950	1 900	5 350	13
	50,000	6 550	5 650	5 300	3 700	4 250	2 350	2 050	2 000	5 950	12
	100,000	8 600	7 450	7 050	4 500	5 250	2 800	2 200	2 300	8 200	8
	150,000	10 000	8 750	8 250	4 900	5 850	3 050	2 230	2 450	9 850	7
	200,000	11 000	9 700	9 150	5 200	6 250	3 250	2 240	2 500	11 200	6
	300,000	12 550	11 200	10 600	5 550	6 850	3 500	-	2 600	13 350	5
	500,000	14 550	13 300	12 600	5 900	7 500	3 750	-	-	16 550	3
	1,000,000	17 300	16 450	15 600	6 200	8 250	-	-	-	21 900	2
	2,000,000	20 000	19 950	18 950	6 300	8 800	-	-	-	28 550	1
	5,000,000	23 050	24 950	23 750	-	-	-	-	-	39 750	1
	10,000,000	-	-	-	-	-	-	-	-	50 300	1

- nil or rounded to zero (including null cells)

Household estimates with relative standard errors of 25% to 50%-2005-06

		NSW	Vic.	Qld	SA	WA	Tas.	NT	ACT	Aust.
		no.	no.	no.	no.	no.	no.	no.	no.	no.

Size of estimate
	Estimate with RSEs of 25%	15 158	11 595	10 104	7 068	8 495	3 515	4 332	3 392	11 312
	Estimate with RSEs of 30%	10 472	8 088	6 990	4 981	6 041	2 505	3 205	2 451	7 704
	Estimate with RSEs of 35%	7 549	5 912	5 069	3 643	4 470	1 860	2 454	1 840	5 528
	Estimate with RSEs of 40%	5 615	4 473	3 807	2 738	3 408	1 424	1 926	1 420	4 124
	Estimate with RSEs of 45%	4 278	3 477	2 938	2 100	2 657	1 117	1 541	1 120	3 170
	Estimate with RSEs of 50%	3 322	2 761	2 317	1 636	2 110	892	1 252	899	2 496

STANDARD ERRORS OF PERSON ESTIMATES-2005-06

		STANDARD ERROR								AUSTRALIA
		NSW	VIC	Qld	SA	WA	Tas.	NT	ACT	Standard error	Relative standard error
		no.	no.	no.	no.	no.	no.	no.	no.	no.	%

Size of estimate
	100	210	210	230	120	150	120	130	140	170	170
	200	360	350	380	230	270	210	230	240	290	145
	300	490	460	500	310	370	290	320	320	390	130
	500	700	650	690	470	540	420	470	450	560	112
	700	880	820	860	600	690	530	600	550	710	101
	1,000	1 120	1 030	1 080	780	890	670	760	690	910	91
	1,500	1 470	1 340	1 380	1 030	1 170	870	980	870	1 190	79
	2,000	1 770	1 600	1 640	1 250	1 400	1 030	1 150	1 020	1 440	72
	2,500	2 050	1 850	1 850	1 450	1 600	1 200	1 300	1 150	1 650	66
	3,000	2 300	2 050	2 100	1 600	1 800	1 300	1 450	1 250	1 850	62
	3,500	2 500	2 250	2 250	1 800	2 000	1 450	1 550	1 350	2 050	59
	4,000	2 700	2 400	2 450	1 900	2 150	1 550	1 650	1 450	2 250	56
	5,000	3 100	2 750	2 800	2 200	2 450	1 750	1 850	1 600	2 550	51
	7,000	3 800	3 350	3 350	2 650	2 900	2 050	2 150	1 900	3 150	45
	10,000	4 650	4 050	4 050	3 200	3 500	2 450	2 500	2 200	3 900	39
	15,000	5 800	5 050	5 000	3 950	4 300	3 000	2 900	2 600	4 900	33
	20,000	6 750	5 850	5 800	4 550	4 950	3 400	3 150	2 850	5 750	29
	30,000	8 350	7 200	7 150	5 500	5 900	4 050	3 550	3 300	7 200	24
	40,000	9 650	8 300	8 200	6 200	6 650	4 500	3 850	3 600	8 400	21
	50,000	10 750	9 200	9 150	6 800	7 300	4 900	4 000	3 850	9 400	19
	100,000	14 900	12 650	12 550	8 800	9 400	6 250	4 550	4 600	13 300	13
	150,000	17 900	15 100	15 050	10 100	10 700	7 050	4 750	5 000	16 150	11
	200,000	20 250	17 050	17 000	11 000	11 650	7 650	4 850	5 300	18 450	9
	300,000	23 950	20 050	20 150	12 300	13 050	8 500	-	5 650	22 100	7
	500,000	29 300	24 400	24 650	13 900	14 700	9 550	-	-	27 500	6
	1,000,000	37 750	31 250	32 050	15 900	16 850	-	-	-	36 350	4
	2,000,000	47 550	39 200	40 850	17 550	18 550	-	-	-	47 100	2
	5,000,000	62 400	51 200	54 850	-	-	-	-	-	64 250	1
	10,000,000	-	-	-	-	-	-	-	-	79 400	1
	15,000,000	-	-	-	-	-	-	-	-	89 000	1
	20,000,000	-	-	-	-	-	-	-	-	96 150	1

- nil or rounded to zero (including null cells)

Person estimates with relative standard errors of 25% to 50%-2005-06

		NSW no.	Vic no.	Qld no.	SA no.	WA no.	Tas. no.	NT no.	ACT no.	Aust. no.

Size of estimate
	Estimate with RSEs of 25%	37 183	27 628	27 148	16 728	19 497	9 741	9 923	7 974	27 433
	Estimate with RSEs of 30%	25 635	19 081	18 803	11 610	13 780	6 767	7 300	5 747	18 321
	Estimate with RSEs of 35%	18 521	13 816	13 672	8 376	10 130	4 894	5 547	4 302	12 861
	Estimate with RSEs of 40%	13 855	10 361	10 307	6 216	7 666	3 647	4 316	3 312	9 369
	Estimate with RSEs of 45%	10 648	7 984	7 991	4 712	5 932	2 780	3 418	2 605	7 023
	Estimate with RSEs of 50%	8 361	6 288	6 335	3 631	4 670	2 157	2 745	2 084	5 386

Standard errors of number of children aged 5-14 years estimate, 2006

		STANDARD ERROR								AUSTRALIA
		NSW	Vic.	Qld.	SA	WA	Tas.	NT	ACT	Standard error	Relative standard error
		no.	no.	no.	no.	no.	no.	no.	no.	no.	%

Size of estimate
	300	430.0	360.0	370.0	270.0	300.0	210.0	210.0	220.0	300.0	100.0
	500	550.0	470.0	460.0	340.0	400.0	270.0	270.0	280.0	400.0	80.0
	700	640.0	560.0	540.0	400.0	470.0	320.0	330.0	330.0	480.0	68.6
	1000	760.0	670.0	640.0	470.0	560.0	370.0	390.0	390.0	580.0	58.0
	1500	920.0	810.0	760.0	560.0	690.0	450.0	470.0	460.0	720.0	48.0
	2000	1 050.0	940.0	870.0	640.0	790.0	510.0	540.0	520.0	840.0	42.0
	2500	1 150.0	1 050.0	950.0	700.0	900.0	550.0	600.0	580.0	950.0	38.0
	3000	1 250.0	1 150.0	1 050.0	750.0	950.0	600.0	650.0	620.0	1 050.0	35.0
	3500	1 350.0	1 200.0	1 100.0	800.0	1 050.0	650.0	700.0	650.0	1 100.0	31.4
	4000	1 450.0	1 300.0	1 200.0	850.0	1 100.0	700.0	750.0	700.0	1 200.0	30.0
	5000	1 600.0	1 450.0	1 300.0	950.0	1 200.0	750.0	800.0	750.0	1 350.0	27.0
	7000	1 900.0	1 700.0	1 550.0	1 100.0	1 400.0	850.0	900.0	900.0	1 600.0	22.9
	10000	2 250.0	2 000.0	1 800.0	1 300.0	1 650.0	950.0	1 050.0	1 000.0	1 900.0	19.0
	15000	2 700.0	2 350.0	2 200.0	1 550.0	1 950.0	1 100.0	1 200.0	1 200.0	2 350.0	15.7
	20000	3 050.0	2 700.0	2 500.0	1 750.0	2 200.0	1 200.0	1 300.0	1 350.0	2 700.0	13.5
	30000	3 700.0	3 200.0	3 000.0	2 050.0	2 650.0	1 350.0	1 500.0	1 550.0	3 250.0	10.8
	40000	4 200.0	3 600.0	3 450.0	2 300.0	2 950.0	1 450.0	1 650.0	1 750.0	3 750.0	9.4
	50000	4 650.0	3 950.0	3 800.0	2 550.0	3 250.0	1 550.0	-	1 900.0	4 150.0	8.3
	100000	6 350.0	5 200.0	5 250.0	3 400.0	4 200.0	1 850.0	-	-	5 750.0	5.8
	150000	7 600.0	6 100.0	6 300.0	4 000.0	4 900.0	-	-	-	6 950.0	4.6
	200000	8 650.0	6 800.0	7 200.0	4 500.0	5 450.0	-	-	-	7 900.0	4.0
	300000	10 350.0	7 900.0	8 700.0	-	6 300.0	-	-	-	9 450.0	3.2
	500000	13 000.0	9 500.0	11 050.0	-	-	-	-	-	11 850.0	2.4
	1000000	17 600.0	12 150.0	15 250.0	-	-	-	-	-	15 950.0	1.6
	2000000	-	-	-	-	-	-	-	-	21 350.0	1.1
	5000000	-	-	-	-	-	-	-	-	31 000.0	0.6
	10000000	-	-	-	-	-	-	-	-	-	. .

. . not applicable
- nil or rounded to zero (including null cells)

Estimates with relative standard errors of 25% to 50%, number of children aged 5-14 years, 2006

		NSW	Vic.	Qld	SA	WA	Tas.	NT	ACT	Aust.
		no.	no.	no.	no.	no.	no.	no.	no.	no.

Size of Estimates
	Estimate with RSEs of 25%	8 077	6 522	5 545	3 102	4 729	2 078	2 302	2 173	5 819
	Estimate with RSEs of 30%	5 752	4 655	3 964	2 236	3 372	1 502	1 650	1 572	4 015
	Estimate with RSEs of 35%	4 313	3 487	2 986	1 693	2 522	1 133	1 233	1 191	2 924
	Estimate with RSEs of 40%	3 359	2 707	2 336	1 329	1 955	881	951	935	2 216
	Estimate with RSEs of 45%	2 692	2 160	1 882	1 073	1 557	702	752	753	1 731
	Estimate with RSEs of 50%	2 208	1 762	1 551	885	1 267	571	606	620	1 386