Rebasing the mid-year population estimates for Scotland · Population Change 1952-2012 Natural...
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Rebasing the mid-year population estimates for Scotland Head of Population and Migration Statistics, National Records of Scotland Population and Migration Statistics Conference 28 November 2013
Transcript of Rebasing the mid-year population estimates for Scotland · Population Change 1952-2012 Natural...
Rebasing the mid-year population estimates for ScotlandHead of Population and Migration Statistics,National Records of Scotland
Population and Migration Statistics Conference28 November 2013
Estimated population of Scotland on 30 June 2012 was 5,313,600
Increase of 18,200 since Census Day, highest ever recorded
4,500,000
4,600,000
4,700,000
4,800,000
4,900,000
5,000,000
5,100,000
5,200,000
5,300,000
5,400,000
1952 1957 1962 1967 1972 1977 1982 1987 1992 1997 2002 2007 2012
Year
Pers
ons
Population Change 1952-2012Natural change and net migration, 1952-2012
-50
-40
-30
-20
-10
0
10
20
30
40
50
1952 1957 1962 1967 1972 1977 1982 1987 1992 1997 2002 2007 2012
Year
Pers
ons
(thou
sand
s)
Natural change (births - deaths) Net Migration
Since Census Day: Natural change: + 6,045 Net migration: + 15,186
Mid-2011 to Mid-2012: Natural change: + 4,223 Net migration: + 12,738
Rest of UK migration +3,000 – little change, 45,100 in-migrants, 42,100 out-
migrants, 3,000 net gain from rest of UK
-70,000
-50,000
-30,000
-10,000
10,000
30,000
50,000
70,000
1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012Year
Pers
ons
In Out Net
Overseas migration + 9,700 much lower than previous three years
drop in in-mig, rise in out-mig
-40,000
-30,000
-20,000
-10,000
0
10,000
20,000
30,000
40,000
50,000
1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012Year
Pers
ons
(000
s)
In Out Net
Council areas: in-migrants as rate per 1,000 of population
0
10
20
30
40
50
60
70
Aber
deen
City
Edi
nbur
gh, C
ity o
f
Stirl
ing
Gla
sgow
City
3
Dun
dee
City
Argy
ll &
But
e
Perth
& K
inro
ss
Eas
t Lot
hian
Mor
ay
East
Ren
frew
shire
Abe
rdee
nshi
re
Sco
ttish
Bor
ders
Ork
ney
Isla
nds
Mid
loth
ian
Ang
us
East
Dun
barto
nshi
re
Sout
h A
yrsh
ire
Eile
an S
iar
Hig
hlan
d
Fife
Cla
ckm
anna
nshi
re
She
tland
Isla
nds
Wes
t Lot
hian
Sout
h La
nark
shire
Nor
th A
yrsh
ire
Dum
fries
& G
allo
way
East
Ayr
shire
Ren
frew
shire
Falk
irk
Wes
t Dun
barto
nshi
re
Nor
th L
anar
kshi
re
Inve
rcly
de
rate
per
1,0
00 p
op'n
within Scotland rest of UK Overseas
0
10
20
30
40
50
60
Abe
rdee
n C
ity
Edin
burg
h, C
ity o
f
Stirl
ing
Gla
sgow
City
3
Dun
dee
City
Arg
yll &
But
e
Perth
& K
inro
ss
East
Lot
hian
Mor
ay
East
Ren
frew
shire
Aber
deen
shire
Sco
ttish
Bor
ders
Ork
ney
Isla
nds
Mid
loth
ian
Angu
s
East
Dun
barto
nshi
re
Sou
th A
yrsh
ire
Eile
an S
iar
Hig
hlan
d
Fife
Cla
ckm
anna
nshi
re
She
tland
Isla
nds
Wes
t Lot
hian
Sout
h La
nark
shire
Nor
th A
yrsh
ire
Dum
fries
& G
allo
way
East
Ayr
shire
Ren
frew
shire
Falk
irk
Wes
t Dun
barto
nshi
re
Nor
th L
anar
kshi
re
Inve
rcly
de
rate
per
1,0
00 p
op'n
within Scotland rest of UK Overseas
Council areas: out-migrants as rate per 1,000 of population
Reconciling the Census with rolled-forward estimates
A lot can happen in ten years…. Population of Scotland, mid-years 1961 to 2001, and variants for 2011
4.8
4.9
5.0
5.1
5.2
5.3
5.4
1961 1971 1981 1991 2001 2011Year
Popu
latio
n (m
illio
ns)
2001-based projection 2001-based Rolled-forward estimate2011 Census-based estimate Historic series
How did we do? Population of Scotland, mid-years 1961 to 2001, and variants for 2011
4.8
4.9
5.0
5.1
5.2
5.3
5.4
1961 1971 1981 1991 2001 2011Year
Popu
latio
n (m
illio
ns)
2001-based projection 2001-based Rolled-forward estimate2011 Census-based estimate Historic series
Difference at Scotland Level
The 2011 Census estimated the population of Scotland to be 5,295,400, which was 49,400 higher than the 5,246,000 given by the rolled-forward estimates based on the previous census – 0.9% of the population.
Thousands
Scotland Rolled-forward
Estimates2011 Census
EstimatesDifference to
explainDifference as % of
Census estimate a b = b - a = ((b - a) / b) * 100Persons 5,246 5,295 49 0.9Males 2,541 2,567 26 1.0Females 2,705 2,728 23 0.9
Differences by age and sex
-15
-10
-5
0
5
10
15
0-4 5-9 10-14 15-19 20-24 25-29 30-34 35-39 40-44 45-49 50-54 55-59 60-64 65-69 70-74 75-79 80-84 85-89 90+
Age group
Diff
eren
ce (t
hous
ands
)
Males
FemalesCensus estimate higher
Rolled-forward estimates higher
Differences by age and sexComparison of sex ratios in the rolled-forward population estimates and the 2011 Census, Scotland,
by age group
30
40
50
60
70
80
90
100
110
120
0-4 5-9 10-14 15-19 20-24 25-29 30-34 35-39 40-44 45-49 50-54 55-59 60-64 65-69 70-74 75-79 80-84 85-89 90+
Age group
Sex
ratio
(mal
es p
er 1
00 fe
mal
es)
Rolled-forward
2011 Census
More females than males
More males than females
Reasons for the Difference•
We expect to find a difference as there are many components involved in estimating population change.
•
Rebasing the mid-year estimates with the latest census results is a key part of the methodology. The 2011 and 2012 estimates reflect this – 2002 to 2010 estimates will be rebased in October/November.
•
The difference at national level due to incomplete accounting for births, deaths, migration, recording of armed forces personnel, definitional differences and imprecision in the two censuses themselves.
•
Difficult to reconcile all these potential sources with each other but they help give reasons why there is a difference.
Reasons for the difference1) Error in the 2001 and 2011 Census bases
(particularly within confidence intervals)2001: +/- 0.33% or +/- 16,7002011: +/- 0.44% or +/- 23,000= up to 39,700
2) Components of the rolling-forward process (particularly migration)= up to 40,000 + 4,400 + ? + ?
3) Definitional differences= up to a few thousand
The rolling forward processprevious population estimate
- prisoners- armed forces
age on by one year+ births
- deaths+/- net migration
+ prisoners+ armed forces
new population estimate
The rolling forward processprevious population estimate
- prisoners‐armed forces
age on by one year+ births
‐
deaths+/- net migration
+ prisoners+ armed forces
new population estimate
The complicated part
Confidence intervals around censuses
• 95 per cent confidence intervals for the total Scottish population in the censuses :
• 2001: +/- 0.33% or +/- 16,700• 2011: +/- 0.44% or +/- 23,000• This means that, we are confident that the true
population of Scotland lay between 5.05 and 5.08 million people in 2001 and between 5.27 and 5.32 million people in 2011.
• A difference as large as 39,700 could be explained due to the levels of confidence around the censuses.
Sex ratios in the 2001-based series
0
20
40
60
80
100
120
0 3 6 9 12 15 18 21 24 27 30 33 36 39 42 45 48 51 54 57 60 63 66 69 72 75 78 81 84 87 90+
Age at mid-year
Sex
ratio
(mal
es p
er 1
00 fe
mal
es)
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
Sex ratios in the 2001-based series
50
60
70
80
90
100
110
0 - 4 5 - 9 10 - 14 15 - 19 20 - 24 25 - 29 30 - 34 35 - 39 40 - 44 45 - 49 50 - 54 55 - 59 60 - 64 65 - 69 70 - 74 75 - 79 80+
Age group in 2011
Sex
ratio
(mal
es p
er 1
00 fe
mal
es)
2011 rolled-forward
2011 Census
2001 Census aged on to 2011
More males than females
More females than males
Note: Ages are estimated as at census day 2011. No data is available from the 2001 Census for those aged 0 to 9 in 2011 as children in this group have been born since the last census.
Components of MigrationAt national level differences due to:• International migration (based on LTIM/IPS)• Cross-border migration (based on NHS
Central Register (NHSCR) Central Health Index (CHI)
At subnational level differences also due to:• Distribution of international and cross-border
migrants• Internal migration within Scotland (based on
NHSCR / CHI)
International migration
International migration - between Scotland and overseas (101,600)
-40,000
-30,000
-20,000
-10,000
0
10,000
20,000
30,000
40,000
50,000
1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012Year
Pers
ons
(000
s)
In Out Net
Confidence intervals around Internation Passenger Survey (IPS) estimates for Scotland,
mid-2001 to mid-2011
Confidence in overseas migration estimates
• Net inward migration of 80,000 used (mid-2001 to mid-2011)
• BUT 95% confidence interval of 39,000 to 120,000 (more people entering than leaving) over the ten years.
• Due to small sample for Scotland – improvements have been made
• Changes to methodology over ten years – would have estimated more migrants using current method
• Potential error in other components
Differences in Council Areas
-20
-15
-10
-5
0
5
10
15
20N
orth
Lan
arks
hire
Hig
hlan
d
Aber
deen
shire
Mor
ay
Angu
s
Ren
frew
shire
Dum
fries
& G
allo
way
Nor
th A
yrsh
ire
East
Ayr
shire
Wes
t Lot
hian
Inve
rcly
de
East
Lot
hian
Scot
tish
Bord
ers
Eile
an S
iar
Aber
deen
City
Sout
h La
nark
shire
Sout
h Ay
rshi
re
Dun
dee
City
Ork
ney
Isla
nds
East
Ren
frew
shire
Mid
loth
ian
Falk
irk
Shet
land
Isla
nds
East
Dun
barto
nshi
re
Cla
ckm
anna
nshi
re
Stir
ling
Wes
t Dun
barto
nshi
re
Argy
ll &
Bute
Fife
Perth
& K
inro
ss
Gla
sgow
City
Edin
burg
h, C
ity o
f
Council area
Diff
eren
ce a
s nu
mbe
r of p
eopl
e (th
ousa
nds)
-10%
-8%
-6%
-4%
-2%
0%
2%
4%
6%
8%
10%
Diff
eren
ce a
s %
of p
opul
atio
n
Number of people (thousands) % of census totalCensus estimates higher
Rolled-forward estimates higher
Estimates for Council Areas
0
100
200
300
400
500
600
700G
lasg
ow C
ity
Edin
burg
h, C
ity o
f
Fife
Nor
th L
anar
kshi
re
Sout
h La
nark
shire
Aber
deen
shire
Hig
hlan
d
Aber
deen
City
Wes
t Lot
hian
Ren
frew
shire
Falk
irk
Dum
fries
& G
allo
way
Dun
dee
City
Perth
& K
inro
ss
Nor
th A
yrsh
ire
East
Ayr
shire
Angu
s
Scot
tish
Bord
ers
Sout
h Ay
rshi
re
East
Dun
barto
nshi
re
East
Lot
hian
Mor
ay
Wes
t Dun
barto
nshi
re
East
Ren
frew
shire
Stirl
ing
Argy
ll &
Bute
Mid
loth
ian
Inve
rcly
de
Cla
ckm
anna
nshi
re
Eile
an S
iar
Shet
land
Isla
nds
Ork
ney
Isla
nds
Council area
Popu
latio
n (th
ousa
nds
of p
eopl
e) Rolled-forward estimates 2011 Census estimates
Distribution of overseas migrants - Out-migration to overseas from each NHS Board area,
2001 to 2011
Cross-border migration
Cross-border migration - between Scotland and the rest of the UK (81,400)
-70,000
-50,000
-30,000
-10,000
10,000
30,000
50,000
70,000
1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012Year
Pers
ons
In Out Net
Cross-border migration flows by age (2010 to 2011)
-2500
-2000
-1500
-1000
-500
0
500
1000
1500
2000
2500
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90
Age
No.
of M
igra
nts
In-migration (from rest of UK)Out-migration (to rest of UK)Net cross-border migration
Peak: 23,24
Peak: 18,19
Difference between Census and rolled-forward estimates
– females, single year of age
Internal, within Scotland migration
Internal & Cross-border Migration – Comparison of differences by age in Edinburgh and
surrounding areas
Internal & Cross-border Migration – Comparison of differences by age in Edinburgh and
surrounding areas
Other Reasons for differences
• Births and deaths well accounted for• Cross-border migration from the rest of
the UK (measured through NHS Central Register & Community Health Index)
• Armed forces & Prisoners• Other groups e.g. students
What does this mean for our estimates?
•
We expect to find a difference as there are many components involved in estimating population change.
•
Rebasing the mid-year estimates with the latest census results is a key part of the methodology.
•
The 2011 and 2012 estimates published in August reflect this – 2002 to 2010 estimates will be rebased on 17 December 2013 to give a consistent time series taking into account the new information from the 2011 Census.
•
We have now reviewed and improved some aspects of our methodology, particularly around international migration distributions.
Further work• Work to improve population estimates is continuing, including
investigating other sources such as:– Higher Education Statistics Agency (HESA) data– Council Tax data
• Further work will use 2011 Census data on previous address and country of birth to evaluate our migration data and assumptions.
• The Scottish Longitudinal Study will use data linkage to compare the Censuses and administrative sources.
• The Beyond 2011 Programme is also exploring the future provision of population statistics in Scotland. As part of this Programme NRS are investigating a range of solutions, to produce population statistics in future.
For further information please view the following publications in the Population Estimates section of the National Records of Scotland website:-
‘Mid-2011 and Mid-2012 Population Estimates’
‘2011 Census Reconciliation Report – Population’
For more information please contact: National Records of Scotland Statistics
Customer Services email: [email protected]
Tel: 0131 314 4299
