General Household Survey, 2005
Sampling Errors
General Household Survey 2005
Sampling Errors
Appendix C
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Office for National Statistics: November 2006
UK Data Archive Study Number 6716 - General Lifestyle Survey, 2000-2008: Secure Data Service Access
General Household Survey, 2005
Sampling Errors Tables in this appendix present estimates of sampling errors for some of the main
variables used in this report, taking into account the complex sample design of the survey.
Sources of error in surveys
Survey results are subject to various sources of error. The total error in a survey estimate is
the difference between the estimate derived from the sample data collected and the true
value for the population. The total error is made up of two main types: systematic and
random error.
Systematic error
Systematic error occurs when data are consistently biased in a certain way, such that the
variation from the true values for the population will not average to zero over repeats of
the survey. For example, if a certain section of the population is excluded from the
sampling frame, estimates may be biased because non-respondents to the survey have
different characteristics to respondents. Another cause of bias may be that interviewers
systematically influence responses in one way or another. Substantial efforts have been
made to avoid systematic errors, for example, through extensive interviewer training and
by weighting the data collected for non-response.
Random error
Random error, or bias, is the variation in sample data from the true values for the
population, which occurs by chance. This type of error is expected to average to zero over a
number of repeats of the survey. Random error may result from sources such as variation
in respondents’ interpretation of the survey questions, or interviewer variation. Efforts are
made to minimise these effects through pilot work and consistent interviewer training.
Sampling errors
An important component of random error is sampling error, which arises because the
variable estimates are based on a sample rather than a full census of the population. The
results obtained for any single sample would be likely to vary slightly from the true values
for the population. The difference between the estimates derived from the sample and the
true population values is referred to as
the sampling error. The amount of variation can generally be reduced by increasing the
size of the sample, and by improving the sample design. Sampling errors have been
measured for estimates derived from the General Household Survey (GHS), and these may
be used to assess the accuracy of the estimates presented in this report.
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General Household Survey, 2005
Sampling Errors
Calculating standard errors
Unlike non-sampling errors, it is possible to estimate the size of sampling error, by
calculating the standard error of the survey estimates. The standard error (se) of a
percentage p, based on a simple random sample of size n is calculated by the formula,
se(p)srs=√(p(100-p)/n).
The GHS uses a multi-stage sample design, which involves both clustering and
stratification (see Appendix B). The complexity of the design means that sampling errors
calculated on the basis of a simple random sample design will not reflect the true variance
in the survey estimates. Clustering can lead to a substantial increase in sampling error if
the households or individuals within the primary sampling units (PSUs) are relatively
homogenous but the PSUs differ from one another. By contrast, stratification tends to
reduce sampling error and is particularly effective when the stratification factor is related
to the characteristics of interest on the survey.
Because of the complexity of the GHS sample design, the size of the standard error
depends on how the characteristic of interest is spread within and between the PSUs and
strata. The method used to calculate the standard errors for the survey takes this into
account. It explicitly allows for the fact that the estimated values (percentages and means)
are ratios of two survey estimates: the number with the characteristic of interest is the
numerator (y) and the sample size is the denominator (x), both of which are subject to
random error.
The standard error of a survey estimate is found by calculating the positive square root of
the estimated variance of the ratio. The formula used to estimate the variance of a ratio
estimator r (where r = y/x) is shown below.
var(r) = 1 [var(y) + r2var (x) - 2r cov(y,x)]
x2
Var(r) is the estimate of the variance of the ratio, r, expressed in terms of var(y) and
var(x) which are the estimated variances of y and x, and cov(y,x) which is their estimated
covariance. The resulting estimate is only valid if the denominator (x) does not vary too
greatly. The method compares the differences between totals for adjacent PSUs (postal
sectors) in the characteristic of interest. The ordering of PSUs reflects the ranking of postal
sectors on the stratifiers used in the sample design.
Design factors
The design factor, or deft, of an estimate p is the ratio of the complex standard error of p to
the standard error of p that would have resulted had the survey design been a simple
random sample of the same size.
deft(p) = se(p)
sesrs(p)
This is often used to give a broad indication of the effect of the clustering on the reliability
of estimates. The size of the design factor varies between survey variables reflecting the
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General Household Survey, 2005
Sampling Errors degree to which a characteristic of interest is clustered within PSUs, or is distributed
between strata. For a single variable the size of the design factor also varies according to
the size of the subgroup on which the estimate is based, and on the distribution of that
subgroup between PSUs and strata. Design factors below 1.0 show that the complex
sample design improved on the estimate that we would have expected from a simple
random sample, probably due to the benefits of stratification. Design factors greater than
1.0 show less reliable estimates than might be gained from a simple random sample, due to
the effects of clustering. Design factors equal to 1.0 indicate no difference in the survey
design on the reliability of the estimate.
The formula to calculate the standard error of the difference between two percentages for a
complex sample design is:
se(p1-p2)=√[deft21(p1(100-p1)/n1)+ deft22 (p2(100-p2)/n2)].
where p1 and p2 are observed percentages for the two sub-samples and n1 and n2 are the
sub-sample sizes.
Confidence intervals
The estimate produced from a sample survey will rarely be identical to the population
value, but statistical theory allows us to measure its accuracy. A confidence interval can be
calculated around the estimated value, which gives a range in which the true value for the
population is likely to fall. The standard error measures the precision with which the
estimates from the sample approximate to the true population values and is used to
construct the confidence interval for each survey estimate.
The 95% confidence intervals have been calculated for each estimated value presented.
These are known as such, because if it were possible to repeat the survey under the same
conditions a number of times, we would expect 95% of the confidence intervals calculated
in this way to contain the true population value for that estimate. When assessing the
results of a single survey, it is usual to assume that there is only a 5% chance that the true
population value falls outside the 95% confidence interval calculated for each survey
estimate. To construct the bounds of the confidence interval, 1.96 times the standard error
is subtracted from, and added to, the estimated value, since under a normal distribution,
95% of values lie within 1.96 standard errors of the mean value. The confidence interval is
then given by:
p +/- 1.96 x se(p).
The 95% confidence interval for the difference between two percentages is given by:
(p1-p2) +/- 1.96 x se (p1-p2).
If this confidence interval includes zero then the observed difference is considered to be a
result of chance variation in the sample. If the interval does not include zero then it is
unlikely (less than 5% probability) that the observed difference could have occurred by
chance.
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Sampling Errors
Standard errors for the 2005 GHS
The standard errors were calculated on weighted data using STATA1. Weighting for
different sampling probabilities results in larger sampling errors than for an equal-
probability sample without weights. However, weighting which uses population totals to
control for differential non-response tends to lead to a reduction in the errors. The method
used to calculate the sampling errors correctly allows for the inflation in the sampling
errors caused by the first type of weighting but, in treating the second type of weighting in
the same way as the first, incorrectly inflates the estimates further. Therefore the standard
errors and defts presented are likely to be slight over-estimates. Weighted data were used
so that the values of the percentages and means were the same as those in the substantive
chapters of the report.
Tables C.1 to C.12 show the standard error, the 95% confidence interval and the deft for
selected survey estimates. The tables do not cover all the topics discussed in the report but
show a selection of estimates.
For the design factors of household based estimates, one was below 1, one fifth (20%) were
below 1.1, just over two fifths (43%) were less than 1.2, and just over two-thirds (70%) of
the defts were less than 1.3. There were three cases (10% of all the household-based
estimates) where the deft was 1.5 or greater. The higher defts were mostly for tenure and
accommodation type (Table C.1) where the effects of clustering lead to a loss of precision
compared with that of a simple random sample. The defts that were below 1.1 were in part
for the number of persons in the household and household type, indicating that
stratification has increased the precision of the sample over a simple random sample for
these estimates of household variables.
For the design factors of person based estimates, 2% were below 1, about a tenth (12%)
were below 1.1, nearly two-thirds (63%) were less than 1.2, and half (50%) of the defts were
less than 1.3. Three per cent of the defts were 1.5 or greater, including many of those for
estimates of ethnicity, shown in Table C.6. As well as clustering in the same sectors, people
from the same ethnic backgrounds will generally cluster within the same households, and
so estimates have high sampling errors and high defts. In contrast, estimates broken down
by gender will generally have lower sampling errors because there is often one man and
one woman in a household; for example, the estimates of males and females in the
population have defts of 0.8 (Table C.4).
Estimating standard errors for other survey measures
The standard errors of survey measures, which are not presented in the tables and for
sample subgroups may be estimated by applying an appropriate value of deft to the
sampling error. The choice of an appropriate value of deft will vary according to whether
the basic survey measure is included in the tables. Since most deft values are relatively
small (1.3 or less) the absolute effect of adjusting sampling errors to take account of the
survey’s complex design will be small. In most cases it will result in an increase of less than
30% over the standard error assuming a simple random sample. Whether it is considered
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Sampling Errors necessary to use deft or to use the basic estimates of standard errors assuming a simple
random sample is a matter of judgement and depends chiefly on the use to which the
survey results are to be put.
Notes and references
1. STATA is a statistical analysis software package. For further details of the method of
calculation see: Elliot D. A comparison of software for producing sampling errors on social
surveys. SSD Survey Methodology Bulletin 1999; 44: 27-36.
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Sampling Errors
Table C1 Standard errors and 95% confidence intervals for household tenure, household type and accommodation type
Base Characteristic % (p ) Deft
All householdsHousehold type1 adult aged 16-59 15.9 12802 0.38 15.1 - 16.6 1.22 adults aged 16-59 16.4 12802 0.36 15.7 - 17.1 1.1Youngest person aged 0-4 10.6 12802 0.27 10.1 - 11.1 1.0Youngest person aged 5-15 15.6 12802 0.34 14.9 - 16.2 1.13 or more adults 10.2 12802 0.34 9.5 - 10.9 1.32 adults, 1 or both aged 60 or over 15.9 12802 0.36 15.2 - 16.6 1.11 adult aged 60 or over 15.4 12802 0.32 14.8 - 16.1 1.0
TenureOwner occupied, owned outright 30.3 12800 0.47 29.4 - 31.2 1.2Owner occupied, with mortgage 38.4 12800 0.51 37.4 - 39.4 1.2Rented from council 12.3 12800 0.46 11.4 - 13.2 1.6Rented from housing association 7.5 12800 0.31 6.8 - 8.1 1.3Rented privately, unfurnished 8.2 12800 0.29 7.7 - 8.8 1.2Rented privately, furnished 3.3 12800 0.26 2.8 - 3.8 1.6
Accommodation typeDetached house 21.9 12802 0.48 21.0 - 22.9 1.3Semi-detached house 30.8 12802 0.55 29.8 - 31.9 1.3Terraced house 27.7 12802 0.58 26.6 - 28.8 1.5Purpose-built flat or maisonette 15.7 12802 0.48 14.8 - 16.7 1.5Converted flat or maisonette/rooms 3.8 12802 0.27 3.2 - 4.3 1.6With business premises/other 0.1 12802 0.02 0.0 - 0.1 0.9
Unweighted sample size
Standard error of p
95% confidence intervals
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Sampling Errors
Table C2 Standard errors and 95% confidence intervals for number of persons and cars at each household
Base Characteristic % (p ) Deft
All householdsNumber of persons1 31.3 12802 0.48 30.4 - 32.3 1.22 35.0 12802 0.46 34.1 - 35.9 1.13 14.8 12802 0.33 14.2 - 15.5 1.14 12.9 12802 0.30 12.3 - 13.5 1.05 4.2 12802 0.17 3.9 - 4.6 1.06 or more 1.7 12802 0.13 1.5 - 2.0 1.1
Number of cars/light vans1 44.8 12802 0.46 43.9 - 45.7 1.02 or more 30.1 12802 0.44 29.2 - 30.9 1.1none 25.1 12802 0.45 24.2 - 26.0 1.2
95% confidence intervals
Unweighted sample size
Standard error of p
Table C3 Standard errors and 95% confidence intervals for households' ownership of selected consumer durables
Base Characteristic % (p ) Deft
All householdsSelected consumer durables
Home computer 63.4 12802 0.50 62.4 - 64.3 1.2
Washing machine 36.6 12802 0.50 35.7 - 37.6 1.2
95% confidence intervals
Unweighted sample size
Standard error of p
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Sampling Errors
Table C4 Standard errors and 95% confidence intervals for age and sex
Base Characteristic % (p ) Deft
SexAll persons Male 48.7 30069 0.24 48.2 - 49.1 0.8
Female 51.3 30069 0.24 50.9 - 51.8 0.8
AgeAll persons 0-4 5.7 30069 0.15 5.4 - 6.0 1.1
5-15 13.8 30069 0.25 13.3 - 14.3 1.316-44 39.8 30069 0.40 39.0 - 40.6 1.445-64 25.0 30069 0.33 24.4 - 25.6 1.365-74 8.5 30069 0.20 8.1 - 8.9 1.275 and over 7.1 30069 0.19 6.8 - 7.5 1.3
All males 0-4 6.0 14580 0.21 5.6 - 6.4 1.15-15 14.3 14580 0.34 13.7 - 15.0 1.216-44 40.3 14580 0.53 39.2 - 41.3 1.345-64 25.3 14580 0.41 24.5 - 26.1 1.165-74 8.3 14580 0.25 7.8 - 8.8 1.175 and over 5.8 14580 0.19 5.4 - 6.2 1.0
All females 0-4 5.4 15489 0.18 5.0 - 5.7 1.05-15 13.3 15489 0.30 12.8 - 13.9 1.116-44 39.4 15489 0.42 38.6 - 40.2 1.145-64 24.7 15489 0.37 24.0 - 25.4 1.165-74 8.7 15489 0.22 8.3 - 9.2 1.075 and over 8.4 15489 0.25 7.9 - 8.9 1.1
95% confidence intervals
Unweighted sample size
Standard error of p
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Sampling Errors
C5 Standard errors and 95% confidence intervals for marital status
Base Characteristic % (p ) Deft
Marital StatusAll persons aged 16 and over Married 51.0 23750 0.50 50.0 - 51.9 1.5
Cohabiting 9.9 23750 0.31 9.2 - 10.5 1.6Single 23.5 23750 0.47 22.6 - 24.5 1.7Widowed 7.1 23750 0.18 6.8 - 7.5 1.1Divorced 6.1 23750 0.17 5.8 - 6.4 1.1Separated 2.1 23750 0.11 1.9 - 2.4 1.2
Men aged 16 and over Married 52.9 11367 0.61 51.7 - 54.1 1.3Cohabiting 10.2 11367 0.32 9.6 - 10.9 1.1Single 26.7 11367 0.60 25.5 - 27.9 1.5Widowed 3.2 11367 0.18 2.9 - 3.6 1.1Divorced 4.8 11367 0.17 4.5 - 5.1 0.9Separated 1.8 11367 0.15 1.5 - 2.0 1.2
Women aged 16 and over Married 49.2 12383 0.52 48.1 - 50.2 1.2Cohabiting 9.5 12383 0.30 8.9 - 10.1 1.1Single 20.6 12383 0.52 19.6 - 21.6 1.4Widowed 10.7 12383 0.30 10.1 - 11.3 1.1Divorced 7.3 12383 0.26 6.8 - 7.8 1.1Separated 2.5 12383 0.15 2.2 - 2.8 1.1
All persons aged 16 to 24 Married 3.8 2990 0.45 2.9 - 4.7 1.3Cohabiting 11.4 2990 0.82 9.8 - 13.0 1.4Single 83.9 2990 0.99 82.0 - 85.9 1.5Widowed 0.0 2990 0.03 0.0 - 0.1 1.0Divorced 0.2 2990 0.09 0.0 - 0.4 1.1Separated 0.4 2990 0.12 0.2 - 0.7 1.0
All persons aged 25 to 34 Married 39.1 3771 1.09 36.9 - 41.2 1.4Cohabiting 22.8 3771 0.93 21.0 - 24.6 1.4Single 32.8 3771 0.98 30.9 - 34.7 1.3Widowed 0.1 3771 0.05 0.0 - 0.2 1.0Divorced 2.2 3771 0.25 1.7 - 2.7 1.0Separated 2.3 3771 0.26 1.8 - 2.8 1.1
All persons aged 35 to 44 Married 60.8 4463 0.93 59.0 - 62.7 1.3Cohabiting 12.0 4463 0.64 10.8 - 13.3 1.3Single 15.3 4463 0.68 13.9 - 16.6 1.3Widowed 0.5 4463 0.12 0.3 - 0.8 1.1Divorced 7.5 4463 0.45 6.6 - 8.4 1.1Separated 3.4 4463 0.31 2.7 - 4.0 1.2
All persons aged 45 to 54 Married 68.2 3819 0.86 66.5 - 69.9 1.1Cohabiting 7.6 3819 0.49 6.6 - 8.6 1.1Single 8.9 3819 0.49 7.9 - 9.9 1.1Widowed 1.3 3819 0.18 0.9 - 1.6 1.0Divorced 10.8 3819 0.55 9.7 - 11.9 1.1Separated 3.0 3819 0.31 2.4 - 3.6 1.1
All persons aged 55 to 64 Married 71.8 3827 0.90 70.1 - 73.6 1.2Cohabiting 4.7 3827 0.45 3.8 - 5.6 1.3Single 6.0 3827 0.42 5.1 - 6.8 1.1Widowed 5.4 3827 0.40 4.6 - 6.2 1.1Divorced 9.6 3827 0.55 8.5 - 10.7 1.2Separated 2.4 3827 0.26 1.9 - 2.9 1.1
All persons aged 65 to 74 Married 66.3 2754 1.05 64.2 - 68.3 1.2Cohabiting 2.0 2754 0.36 1.3 - 2.7 1.4Single 4.7 2754 0.42 3.9 - 5.5 1.0Widowed 17.6 2754 0.80 16.0 - 19.2 1.1Divorced 8.1 2754 0.55 7.0 - 9.1 1.1Separated 1.4 2754 0.24 1.0 - 1.9 1.1
All persons aged 75 and over Married 42.8 2126 1.27 40.3 - 45.3 1.2Cohabiting 1.0 2126 0.29 0.5 - 1.6 1.3Single 6.2 2126 0.60 5.0 - 7.3 1.2Widowed 46.2 2126 1.32 43.6 - 48.8 1.2Divorced 3.0 2126 0.39 2.2 - 3.7 1.1Separated 0.8 2126 0.19 0.4 - 1.2 1.0
Unweighted sample size
Standard error of p
95% confidence intervals
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General Household Survey, 2005
Sampling Errors
Table C.6 Standard errors and 95% confidence intervals for ethnic origin*
Base1 Characteristic % (p ) Deft
All persons aged 16 and over Ethnic Origin
White 91.0 23706 0.46 90.1 - 91.9 2.5Mixed Race 0.8 23706 0.08 0.6 - 1.0 1.4Asian-Indian 2.1 23706 0.21 1.6 - 2.5 2.3Asian- Pakistani, Bangladeshi, Other 2.4 23706 0.25 2.0 - 2.9 2.5Black Caribbean 1.1 23706 0.12 0.9 - 1.4 1.8Black African 1.3 23706 0.12 1.0 - 1.5 1.7Other 1.4 23706 0.14 1.1 - 1.6 1.9
* Other includes other Black groups. Information on those giving no answer has not been presented1 These estimates are based on 2005 data only, wheras in the report estimates are based on 2001, 2002 and 2003 data combined.We would expect the defts to be very similar for the combined years estimates.
Unweighted sample size
Standard error of p
95% confidence intervals
Table C.7 Standard errors and 95% confidence intervals for education level
Base Characteristic % (p ) Deft
Education levelAll persons aged 16 to 69 Higher education 28.5 20174 0.49 27.6 - 29.5 1.5
Other qualifications 45.2 20174 0.44 44.4 - 46.1 1.3None 26.2 20174 0.46 25.3 - 27.1 1.5
All men aged 16 to 69 Higher education 29.4 9336 0.59 28.2 - 30.5 1.3Other qualifications 46.8 9336 0.59 45.6 - 47.9 1.1None 23.9 9336 0.55 22.8 - 24.9 1.2
All women aged 16 to 69 Higher education 27.8 10838 0.56 26.7 - 28.9 1.3Other qualifications 43.9 10838 0.53 42.8 - 44.9 1.1None 28.3 10838 0.53 27.3 - 29.3 1.2
95% confidence intervals
Unweighted sample size
Standard error of p
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Sampling Errors
Table C8 Standard errors and 95% confidence intervals for socio-economic classification and employment status of adults
Base Characteristic % (p ) Deft
Socio-economic classification
All persons aged 16 and over Higher managerial and professional 11.0 23750 0.26 10.5 - 11.5 1.3
Lower managerial and professional 22.8 23750 0.35 22.1 - 23.5 1.3
Intermediate 12.9 23750 0.24 12.4 - 13.4 1.1
Small employers and own account 7.8 23750 0.19 7.4 - 8.2 1.1
Lower supervisory and technical 9.0 23750 0.22 8.6 - 9.5 1.2
Semi-routine 17.6 23750 0.31 16.9 - 18.2 1.3
Routine 14.1 23750 0.30 13.5 - 14.7 1.3
Never worked and long-term unemployed 4.9 23750 0.19 4.5 - 5.2 1.4
Higher managerial and professional 16.3 10525 0.42 15.5 - 17.1 1.2
Lower managerial and professional 21.7 10525 0.42 20.9 - 22.5 1.1Intermediate 6.3 10525 0.26 5.8 - 6.8 1.1Small employers and own account 11.2 10525 0.31 10.6 - 11.8 1.0
Lower supervisory and technical 13.3 10525 0.38 12.5 - 14.0 1.2Semi-routine 12.2 10525 0.36 11.5 - 12.9 1.1Routine 15.7 10525 0.42 14.9 - 16.5 1.2Never worked and long-term unemployed 3.4 10525 0.23 2.9 - 3.8 1.3
Higher managerial and professional 6.1 11546 0.24 5.7 - 6.6 1.1Lower managerial and professional 23.9 11546 0.45 23.0 - 24.7 1.1Intermediate 18.9 11546 0.36 18.2 - 19.7 1.0
Small employers and own account 4.6 11546 0.21 4.2 - 5.0 1.1Lower supervisory and technical 5.1 11546 0.22 4.7 - 5.6 1.1Semi-routine 22.5 11546 0.44 21.6 - 23.3 1.1Routine 12.7 11546 0.34 12.0 - 13.3 1.1
Never worked and long-term unemployed 6.2 11546 0.27 5.7 - 6.7 1.2
Higher managerial and professional 11.8 9778 0.38 11.1 - 12.5 1.2Lower managerial and professional 24.2 9778 0.49 23.3 - 25.2 1.1Intermediate 13.6 9778 0.36 12.9 - 14.3 1.0Small employers and own account 6.3 9778 0.27 5.7 - 6.8 1.1Lower supervisory and technical 8.1 9778 0.30 7.5 - 8.7 1.1
Semi-routine 16.9 9778 0.43 16.1 - 17.8 1.1Routine 12.0 9778 0.40 11.2 - 12.8 1.2Never worked and long-term unemployed 7.1 9778 0.31 6.5 - 7.7 1.2
Higher managerial and professional 12.2 7465 0.41 11.4 - 13.0 1.1
Lower managerial and professional 23.8 7465 0.54 22.8 - 24.9 1.1Intermediate 11.9 7465 0.37 11.1 - 12.6 1.0Small employers and own account 9.8 7465 0.38 9.0 - 10.5 1.1Lower supervisory and technical 8.8 7465 0.34 8.2 - 9.5 1.0Semi-routine 17.4 7465 0.49 16.4 - 18.3 1.1Routine 13.8 7465 0.46 12.9 - 14.7 1.2Never worked and long-term unemployed 2.4 7465 0.20 2.0 - 2.8 1.1
Higher managerial and professional 7.9 2731 0.57 6.8 - 9.0 1.1Lower managerial and professional 18.6 2731 0.86 16.9 - 20.3 1.2
Intermediate 11.8 2731 0.63 10.6 - 13.1 1.0Small employers and own account 8.9 2731 0.59 7.7 - 10.1 1.1Lower supervisory and technical 11.9 2731 0.69 10.6 - 13.3 1.1Semi-routine 17.9 2731 0.78 16.4 - 19.4 1.1Routine 19.7 2731 0.84 18.1 - 21.4 1.1Never worked and long-term unemployed 3.3 2731 0.41 2.5 - 4.1 1.2
Higher managerial and professional 6.7 2097 0.58 5.6 - 7.9 1.1
Lower managerial and professional 17.5 2097 0.85 15.8 - 19.1 1.0Intermediate 14.1 2097 0.84 12.5 - 15.8 1.1Small employers and own account 6.9 2097 0.62 5.7 - 8.1 1.1
Lower supervisory and technical 10.8 2097 0.66 9.5 - 12.1 1.0Semi-routine 20.8 2097 0.96 18.9 - 22.7 1.1Routine 18.8 2097 0.96 16.9 - 20.6 1.1Never worked and long-term unemployed 4.4 2097 0.46 3.5 - 5.3 1.0
Employment statusAll persons aged 16 & over In employment 59.5 23381 0.46 58.6 - 60.4 1.4
Unemployed 2.4 23381 0.12 2.2 - 2.7 1.2Economically inactive 38.1 23381 0.46 37.2 - 39.0 1.5
In employment 65.9 11135 0.57 64.8 - 67.0 1.3Unemployed 3.0 11135 0.18 2.7 - 3.4 1.1Economically inactive 31.1 11135 0.55 30.0 - 32.2 1.3
In employment 53.7 12246 0.53 52.7 - 54.7 1.2
Unemployed 1.9 12246 0.13 1.6 - 2.1 1.1Economically inactive 44.5 12246 0.53 43.4 - 45.5 1.2
All persons aged 65 to 74
All persons aged 75 and over
All men aged 16 and over
All women aged 16 and over
All men aged 16 and over
All women aged 16 and over
All persons aged 16 to 44
All persons aged 45 to 64
Unweighted sample size
Standard error of p
95% confidence intervals
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Sampling Errors
Table C.9 Standard errors and 95% confidence intervals for health measures
Base Characteristic % (p ) Deft
Self-reported sicknessAll persons Longstanding illness 32.8 28206 0.46 31.9 - 33.7 1.7
Limiting longstanding illness 18.2 29708 0.30 17.6 - 18.8 1.3Restricted activity in the last 14 days 13.1 28210 0.29 12.5 - 13.7 1.4
All males Longstanding illness 32.3 13394 0.51 31.3 - 33.3 1.3Limiting longstanding illness 17.0 14353 0.36 16.2 - 17.7 1.2Restricted activity in the last 14 days 11.4 13397 0.34 10.8 - 12.1 1.2
All females Longstanding illness 33.3 14812 0.54 32.3 - 34.4 1.4Limiting longstanding illness 19.3 15355 0.40 18.5 - 20.1 1.3Restricted activity in the last 14 days 14.6 14813 0.37 13.9 - 15.3 1.3
All persons aged Longstanding illness 12.0 1819 0.86 10.3 - 13.7 1.10 to 4 Limiting longstanding illness 3.8 1901 0.46 2.9 - 4.7 1.1
Restricted activity in the last 14 days 9.1 1892 0.75 7.6 - 10.6 1.1
All persons aged Longstanding illness 17.5 4401 0.72 16.1 - 18.9 1.35 to 15 Limiting longstanding illness 7.1 4418 0.43 6.3 - 8.0 1.1
Restricted activity in the last 14 days 8.3 4401 0.49 7.3 - 9.3 1.2
All persons aged Longstanding illness 22.6 10000 0.53 21.6 - 23.7 1.316 to 44 Limiting longstanding illness 11.2 10965 0.35 10.5 - 11.9 1.2
Restricted activity in the last 14 days 10.8 10000 0.36 10.1 - 11.5 1.2
All persons aged Longstanding illness 43.5 7194 0.72 42.1 - 44.9 1.245 to 64 Limiting longstanding illness 24.6 7562 0.57 23.5 - 25.7 1.2
Restricted activity in the last 14 days 15.9 7196 0.51 14.9 - 16.9 1.2
All persons aged Longstanding illness 59.7 2673 1.13 57.5 - 61.9 1.265 to 74 Limiting longstanding illness 36.3 2747 0.95 34.4 - 38.2 1.0
Restricted activity in the last 14 days 18.3 2675 0.86 16.6 - 20.0 1.2
Longstanding illness 64.4 2047 1.25 61.9 - 66.8 1.2Limiting longstanding illness 45.2 2115 1.17 42.9 - 47.5 1.1Restricted activity in the last 14 days 21.7 2046 1.11 19.5 - 23.9 1.2
Unweighted sample size
Standard error of p
95% confidence intervals
All persons aged 75+
Office for National Statistics: November 2006 page 13
General Household Survey, 2005
Sampling Errors
Table C.10 Standard errors and 95% confidence intervals for cigarette smoking
Base Characteristic % (p ) Deft
Cigarette smokingAll persons aged 16 & over Current cigarette smoker 23.9 21665 0.37 23.2 - 24.6 1.3
Ex-regular cigarette smoker 23.7 21665 0.35 23.0 - 24.4 1.2Never regularly smoked cigarettes 52.5 21665 0.46 515.6 - 53.4 1.4
Current cigarette smoker 25.3 10038 0.50 24.3 - 26.3 1.2Ex-regular cigarette smoker 27.3 10038 0.52 26.2 - 28.3 1.2Never regularly smoked cigarettes 47.5 10038 0.61 46.3 - 48.7 1.2
Current cigarette smoker 22.7 11627 0.42 21.9 - 23.5 1.1Ex-regular cigarette smoker 20.5 11627 0.39 19.8 - 21.3 1.0Never regularly smoked cigarettes 56.8 11627 0.53 55.8 - 57.8 1.2
All women aged 16 and over
Unweighted sample size
Standard error of p
95% confidence intervals
All men aged 16 and over
Office for National Statistics: November 2006 page 14
General Household Survey, 2005
Sampling Errors
Table C11 Standard errors and 95% confidence intervals for alcohol consumption (maximum daily amount)
Base Characteristic % (p ) Deft
Alcohol consumption(maximum daily amount)
All men aged 16 and over Drank nothing last week 27.8 10028 0.54 26.7 - 28.8 1.2Drank up to 4 units 37.6 10028 0.56 36.5 - 38.7 1.2Drank more than 4 and up to 8 units 16.0 10028 0.39 15.3 - 16.8 1.1Drank more than 8 units 18.6 10028 0.45 17.7 - 19.5 1.2
All women aged 16 and over Drank nothing last week 43.1 11617 0.57 42.0 - 44.2 1.2Drank up to 3 units 36.8 11617 0.49 35.8 - 37.7 1.1Drank more than 3 and up to 6 units 12.3 11617 0.34 11.6 - 13.0 1.1Drank more than 6 units 7.8 11617 0.31 7.2 - 8.5 1.2
All aged 16 to 24 Drank nothing last week 40.4 2384 1.36 37.7 - 43.1 1.4Drank up to 4/3 units 20.5 2384 0.98 18.6 - 22.4 1.2Drank more than 4/3 and up to 8/6 units 13.6 2384 0.80 12.1 - 15.2 1.1Drank more than 8/6 units 25.5 2384 1.07 23.4 - 27.6 1.2
All aged 25 to 44 Drank nothing last week 32.3 7444 0.68 31.0 - 33.7 1.3Drank up to 4/3 units 34.1 7444 0.65 32.8 - 35.3 1.2Drank more than 4/3 and up to 8/6 units 16.0 7444 0.45 15.1 - 16.9 1.1Drank more than 8/6 units 17.6 7444 0.53 16.6 - 18.7 1.2
All aged 45 to 64 Drank nothing last week 31.3 7125 0.63 30.1 - 32.5 1.2Drank up to 4/3 units 42.6 7125 0.67 41.3 - 43.9 1.1Drank more than 4/3 and up to 8/6 units 16.6 7125 0.51 15.6 - 17.6 1.2Drank more than 8/6 units 9.5 7125 0.37 8.8 - 10.2 1.1
All aged 65 and over Drank nothing last week 46.5 4692 0.84 44.9 - 48.2 1.2Drank up to 4/3 units 44.3 4692 0.80 42.7 - 45.9 1.1Drank more than 4/3 and up to 8/6 units 7.0 4692 0.41 6.2 - 7.8 1.1Drank more than 8/6 units 2.2 4692 0.23 1.7 - 2.6 1.1
All aged 16 and over Drank nothing last week 35.9 21645 0.45 35.1 - 36.8 1.4Drank up to 4/3 units 37.2 21645 0.41 36.4 - 38.0 1.3Drank more than 4/3 and up to 8/6 units 14.0 21645 0.27 13.5 - 14.6 1.1Drank more than 8/6 units 12.9 21645 0.30 12.3 - 13.4 1.3
Unweighted sample size
Standard error of p
95% confidence intervals
Office for National Statistics: November 2006 page 15
General Household Survey, 2005
Sampling Errors
Office for National Statistics: November 2006 page 16
Table C12 Standard errors and 95% confidence intervals for number of cohabitations
Base Characteristic % (p ) Deft
Number of cohabitationsAll women aged 16 to 59 None 83.1 8065 0.49 82.2 - 84.1 1.2
One 13.0 8065 0.42 12.2 - 13.8 1.1Two or more 3.9 8065 0.22 3.4 - 4.3 1.0
All men aged 16 to 59 None 84.4 6975 0.49 83.5 - 85.4 1.1One 10.6 6975 0.40 9.8 - 11.4 1.1Two or more 5.0 6975 0.29 4.4 - 5.5 1.1
All people aged 16 to 24 None 91.3 2369 0.60 90.1 - 92.5 1.0One 7.4 2369 0.50 6.4 - 8.4 0.9Two or more 1.3 2369 0.25 0.8 - 1.8 1.1
All people aged 25 to 34 None 76.1 2306 0.88 74.4 - 77.8 1.0One 17.5 2306 0.75 16.0 - 18.9 1.0Two or more 6.5 2306 0.48 5.5 - 7.4 0.9
All people aged 35 to 44 None 77.2 3976 0.76 75.7 - 78.7 1.1One 15.9 3976 0.63 14.7 - 17.1 1.1Two or more 6.9 3976 0.49 5.9 - 7.9 1.2
All people aged 45 to 54 None 88.0 3484 0.63 86.8 - 89.2 1.1One 8.6 3484 0.52 7.6 - 9.7 1.1Two or more 3.4 3484 0.31 2.8 - 4.0 1.0
All people aged 55 to 59 None 93.3 1895 0.67 92.0 - 94.6 1.2One 5.2 1895 0.57 4.1 - 6.4 1.1Two or more 1.5 1895 0.34 0.8 - 2.2 1.2
All people aged 16 to 59 None 83.7 15040 0.39 83.0 - 84.5 1.3One 11.9 15040 0.32 11.2 - 12.5 1.2Two or more 4.4 15040 0.19 4.0 - 4.8 1.1
Unweighted sample size
Standard error of p
95% confidence intervals