ukpopulation: UK Demographic Projections

Latest Release: 1.2.2

• update to 2018 mid-year population estimates
• fixes for changed data formats for some of the subnational population projections
• credit and thanks to @BenjaminIsaac0111 and @ld_archer for the work

1.2 Release

Adds support for custom subnational population projections.

Custom SNPP Data

An externally generated SNPP dataset (from e.g. simim) can be registered with the ukpopulation package and used as if it was the standard ONS/StatsWales/NRScotland/NISRA projection:

```python3

import ukpopulation.customsnppdata as CustomSNPPData customdata = pd.readcsv("customsnpp.csv") customdata.head() GEOGRAPHYCODE GENDER CAGE OBSVALUE PROJECTEDYEARNAME 0 E06000005 1 0 603.0 2018 1 E06000005 1 1 600.0 2018 2 E06000005 1 2 624.0 2018 3 E06000005 1 3 636.0 2018 4 E06000005 1 4 661.0 2018 CustomSNPPData.registercustomprojection("customsnpp", customdata, "cachedirectory") Writing custom SNPP customsnpp to cache/ukpopulationcustomsnppcustomsnpp.csv CustomSNPPData.listcustomprojections("cachedirectory") ['customsnpp']

```

The external dataset must follow the format/column name conventions as above, but can also contain extra data if required for other use. The GENDER column should only take the values 1 (male) or 2 (female); the C_AGE column should contain the range 0-90 inclusive (90 meaning 90 or over).

1.1 release

• adds UK household projections
• initial support for custom SNPP variants
• better consistency across the MYE/NPP/SNPP APIs (breaks backwards compatibility)
• fixes some bugs/issues

Household Projections

Version 1.1 adds functionality is aggregates household projection data for the UK at LAD (or equivalent level). Each country's statistical agency provides a disaggregation by household type, but as there is little or no consistency between them, no attempt has (yet) been made to provide a UK-wide unified disaggregation. The year ranges mirror the year ranges for the SNPP for each country (see below). Extrapolation, or application of a national projection variant to the data is not provided at this stage.

Custom SNPP Variants

Given externally-generated data describing variations to an official projection variant, by geography (LAD) and year, this new functionality generates a full SNPP dataset, disaggregated proportionately by age and gender. The custom variant can optionally be forced to nearest-integer values, preserving the original (rounded) total.

API consistency

The public methods of the MYEData, SNPPData, NPPData and SNHPData classes now consistently order arguments: firstly categories (where appropriate) then geogs, then years.

The statistical agencies of the United Kingdom, that is: ONS, StatsWales, NR Scotland, and NISRA, all produce annual population estimates and projection data. Although the data are essentially the same, the quantity, format, and availability varies between agencies and datasets. All of the population projection data is available by (single year of) age and gender. Household projection data is more varied, with each country/agency producing inconsistent disaggregations of households in terms of HRP age and/or household type. For now, this package does not disaggregate by age and leaves the household type disaggregations as-is, which are:

Lowest common denominator | England (ONS) | Wales (StatsWales) | Scotland (NRScotland) | N.Ireland (NISRA) | --------------------------|-----------------------------------------------------|--------------------|-----------------------|--------------------| Single person | 'One person households: Female'
'One person households: Male' |'1 person'|'1 adult: female'
'1 adult: male'|'One adult households'| Adults and children | 'Households with one dependent child'
'Households with three or more dependent children'
'Households with two dependent children' | '2 person (1 adult, 1 child)'
'3 person (2 adults, 1 child)'
'3 person (1 adult, 2 children)'
'4 person (2+ adults, 1+ children)'
'4 person (1 adult, 3 children)'
'5+ person (2+ adults, 1+ children)'
'5+ person (1 adult, 4+ children)'| '1 adult 1+ children'
'2+ adults 1+ children'| 'One adult households with children'
'Other households with children'| Adults only | 'Other households with two or more adults'| '2 person (No children)'
'3 person (No children)'
'4 person (No children)'
'5+ person (No children)'| '2 adults'
'3+ adults'| 'Two adults without children'
'Other households without children'

National population projections (NPP) are the responsibility of ONS who provide the data for each country within the UK, including 15 variants covering a number of possible future scenarios. The current data is based on 2018 population estimates and project a century to 2118.

Subnational population projections (SNPP) are the responsibility of each country's agencies (ONS for England), and project 25 years from a base year that depends on the country in question:

Country | Latest SNPP year range (as of May 2020) | -----------------|------------------------------------------| England | 2018-2043 | Wales | 2018-2043 | Scotland | 2018-2043 | Northern Ireland | 2016-2041 |

Mid-year population estimates (MYE) are available for the entire UK by local authority, single year of age and gender, from 1991 to 2016 inclusive.

Projection Coverage

The countries within the UK produce their own SNPP data, and also produce some (patchy) variant projections. The ONS currently regard these (the England ones at least) as "experimental".

Scenario/Variant | Code | E | S | W | N |NPP| ---------------------------------|------|---|---|---|---|---| Principal | ppp | x | x | x | x | x | High fertility | hpp | x | x | | | x | Low fertility | lpp | | x | | | x | High life expectancy | php | | x | | | x | Low life expectancy | plp | | x | | | x | Moderately high life expectancy | pjp | | | | | x | Moderately low life expectancy | plp | | | | | x | High migration | pph | | x | | | x | Low migration | ppl | | x | | | x | High population | hhh | | | x | | x | Low population | lll | | | x | | x | 0% future EU migration | ppq | | | | | x | 50% future EU migration | ppr | | | | | x | 150% future EU migration | pps | | | | | x | Zero net migration | ppz | x | x | x | | x | Young age structure | hlh | | | | | | Old age structure | lhl | | | | | | Replacement fertility | rpp | | | | | | Constant fertility | cpp | | | | | | No mortality improvement | pnp | | | | | | No change | cnp | | | | | | Long term balanced net migration | ppb | | | x | | |

Accessibility

Nomisweb provides an API which allows relatively easy programmatic access the to data, and by far the preferred source of data. Currently not all the data is available from this source but this may change.

Nomisweb currently hosts the ONS principal NPP data for the UK, the SNPP data for England, and all of the MYE data.

All other data: ONS NPP variants, SNPP data for Wales, Scotland and Northern Ireland are available in different formats from the appropriate agency's website.

Rationale

The purpose of this package is to provide a unified interface to both SNPP and NPP data, including variants:

• encapsulating the downloading, processing and caching of the NPP and SNPP data from the various sources.
• consistently differentiating by age (single year, up to 90) and gender over the various datasets.
• providing a unified format for all the data.
• providing a method of synthesising SNPP variant projections using SNPP principal and NPP principal/variant projections
• providing a method of extrapolating SNPP data using NPP data
• enabling easy filtering and aggregating of of the data, e.g. extracting projections of the working-age population.

Methodology and Detail

Data Sources

• Nomisweb: UK NPP by country/age/gender, England SNPP by LAD/age/gender, UK MYE by LAD/age/gender.
• ONS: UK NPP variants by country/age/gender.
• Stats Wales: Wales SNPP by LAD/age/gender.
• National Records of Scotland: Scotland SNPP by LAD equivalent/age/gender.
• Northern Ireland Statistics and Research Agency: Northern Ireland SNPP by LAD equivalent/age/gender.

Data Processing

• Note that the SNPP for each country, and the NPP data may not have the same reference year. (See table above).
• NPP data is broken down by country (England/Wales/Scotland/Northern Ireland), for all the variant projections indicated in the second table above.
• Column headings and category values follow the nomisweb/census conventions:
  • GEOGRAPHY_CODE: ONS country, LAD, or LAD-equivalent code
  • GENDER: 1=Male, 2=Female
  • C_AGE: 0-90, where 90 represents 90 or over. To avoid ambiguity, this is an exception - nomisweb census values are typically age+1)
  • PROJECTED_YEAR_NAME: 2014-2116
  • OBS_VALUE: count of persons
• All data are cached for swift retrieval.
  

Extrapolation

The SNPP data can be extrapolated using the longer-term NPP data. This is done independently for each age and gender in order to try to capture the age-gender structure of the original population. Aggregation only takes place on the extrapolated age-gender specific values. This means that the trends shown by SNPP geographies with different age-gender structures will differ.

If, conversely, the extrapolation was done on the aggregated populations for each SNPP geography, then each SNPP geography would have an identical trend, which would be identical to that of the NPP data.

This methodology can be more formally explained by the following equation for the aggregate SNPP S(g,y) for a given geography and year:

where N is the NPP, a is age, s is gender, y bar is a reference year (typically the final year in the SNPP data), and c(g) represents a mapping from a SNPP geography (LAD) to a NPP one (country).

Projection of Variants

The extrapolation methodology above can equally be applied to synthesising SNPP variants from SNPP principal and NPP variant data. The equivalent expression to the above is:

where the subscripts V and 0 refer to the variant and the principal projections respectively.

Installation

Requirements

API Key

This package uses the UKCensusAPI package to obtain some of the projection data. The package requires an API key to function correctly, see here for details.

Package

Requires Python 3.5 or higher. Dependencies should resolve automatically, but if not see troubleshooting

PyPI

bash python3 -m pip install ukpopulation

Conda

bash conda install ukpopulation

This assumes you have added the conda-forge channel, which can be done with

bash conda config --add channels conda-forge

Some of the examples (see below) plot graphs and have a dependency on matplotlib, which can be installed with either pip or conda as appropriate.

Development version

To clone the repo and install locally:

bash git clone https://github.com/nismod/ukpopulation ./setup.py install

(substituting the URL if a fork has been taken). The test data cache directory contains a file NOMIS_API_KEY which defines a dummy key for testing purposes only. The test suite can be run from the (project root dir) using:

bash ./setup.py test

Troubleshooting

Ensure you are using the correct version (>=3) of pip:

bash pip --version pip 9.0.1 from /usr/lib/python3/dist-packages (python 3.6)

If not replace pip with pip3 or python3 -m pip

If the installation has missing dependencies, try:

bash pip install -r requirements.txt ./setup.py install

If (with python 3.5?) you encounter

bash AttributeError: module 'html5lib.treebuilders' has no attribute '_base'

then

bash pip install html5lib=0.9999999

should fix it. But better solution is to upgrade to python3.6

If matplotlib fails to install due to a missing dependency (tkinter), this can be fixed on Debian variants by

bash sudo apt install python3-tk

If your problem isn't addressed above, please post an issue including as much supporting information as possible.

Usage Examples

Retrieve SNPP for specific LADs

Detailed data

This example fetches the 2018 projection for Newcastle by gender and age.

```python

import ukpopulation.snppdata as SNPPData snpp = SNPPData.SNPPData() ```

text Cache directory: ./raw_data/ using cached LAD codes: ./raw_data/lad_codes.json Collating SNPP data for England... ./raw_data/NM_2006_1_metadata.json found, using cached metadata... Using cached data: ./raw_data/NM_2006_1_56aba41fc0fab32f58ead6ae91a867b4.tsv ./raw_data/NM_2006_1_metadata.json found, using cached metadata... Using cached data: ./raw_data/NM_2006_1_dbe6c087fb46306789f7d54b125482e4.tsv Collating SNPP data for Wales... Collating SNPP data for Scotland... Collating SNPP data for Northern Ireland...

```python

newcastle=snpp.filter("E08000021", 2018) newcastle.head() ```

text C_AGE GENDER GEOGRAPHY_CODE OBS_VALUE PROJECTED_YEAR_NAME 0 0 1 E08000021 1814.0 2018 1 1 1 E08000021 1780.0 2018 2 2 1 E08000021 1770.0 2018 3 3 1 E08000021 1757.0 2018 4 4 1 E08000021 1747.0 2018

Aggregated data

This example fetches the total population projections for Newcastle from 2018 to 2039.

```python

import ukpopulation.snppdata as SNPPData snpp = SNPPData.SNPPData() ```

Cache directory: ./raw_data/ using cached LAD codes: ./raw_data/lad_codes.json Collating SNPP data for England... ./raw_data/NM_2006_1_metadata.json found, using cached metadata... Using cached data: ./raw_data/NM_2006_1_56aba41fc0fab32f58ead6ae91a867b4.tsv ./raw_data/NM_2006_1_metadata.json found, using cached metadata... Using cached data: ./raw_data/NM_2006_1_dbe6c087fb46306789f7d54b125482e4.tsv Collating SNPP data for Wales... Collating SNPP data for Scotland... Collating SNPP data for Northern Ireland... python

newcastle=snpp.aggregate(["GENDER", "C_AGE"], "E08000021", range(2018,2039)) newcastle.head() ```

GEOGRAPHY_CODE PROJECTED_YEAR_NAME OBS_VALUE 0 E08000021 2018 299132.0 1 E08000021 2019 300530.0 2 E08000021 2020 301699.0 3 E08000021 2021 302729.0 4 E08000021 2022 303896.0

Retrieve NPP data filtered by age

Here's how to get the total working-age population by country from 2016 to 2050:

```python

import ukpopulation.nppdata as NPPData npp = NPPData.NPPData() ```

Cache directory: ./raw_data/ using cached LAD codes: ./raw_data/lad_codes.json Loading NPP principal (ppp) data for England, Wales, Scotland & Northern Ireland ./raw_data/NM_2009_1_metadata.json found, using cached metadata... Using cached data: ./raw_data/NM_2009_1_444caf1f672f0646722e389963289973.tsv

```python

ukworkingage=npp.aggregate(["GENDER", "CAGE"], "ppp", NPPData.NPPData.UK, range(2016,2051), ages=range(16,75)) ukworkingage.head() GEOGRAPHYCODE PROJECTEDYEARNAME OBS_VALUE 0 E92000001 2016 40269470 1 E92000001 2017 40460118 2 E92000001 2018 40591965 3 E92000001 2019 40704521 4 E92000001 2020 40834471 ```

And this aggregates the figures for Great Britain:

```python

gbworkingage=npp.aggregate(["GEOGRAPHYCODE", "GENDER", "CAGE"], "ppp", NPPData.NPPData.GB, range(2016,2051), ages=range(16,75)) gbworkingage.head() PROJECTEDYEARNAME OBS_VALUE 0 2016 46590014 1 2017 46801693 2 2018 46944219 3 2019 47063069 4 2020 47201882 ```

NB SNPP data can also be filtered by age and/or gender and/or geography in the same way.

Retrieve NPP variants for England & Wales

First detailed data (by age, gender and country), then aggregated by age and gender.

```python

import ukpopulation.nppdata as NPPData npp=NPPData.NPPData() Cache directory: ./rawdata/ using cached LAD codes: ./rawdata/ladcodes.json Loading NPP principal (ppp) data for England, Wales, Scotland & Northern Ireland ./rawdata/NM20091metadata.json found, using cached metadata... Using cached data: ./rawdata/NM20091444caf1f672f0646722e389963289973.tsv highgrowth = npp.detail("hhh", NPPData.NPPData.EW) highgrowth.head() CAGE GENDER OBSVALUE PROJECTEDYEARNAME GEOGRAPHYCODE 0 0 1 343198 2016 E92000001 1 0 1 334025 2017 E92000001 2 0 1 345332 2018 E92000001 3 0 1 349796 2019 E92000001 4 0 1 354274 2020 E92000001 highgrowthagg = npp.aggregate(["GENDER", "CAGE"], "hhh", NPPData.NPPData.EW) highgrowthagg.head() GEOGRAPHYCODE PROJECTEDYEARNAME OBS_VALUE 0 E92000001 2016 55268067 1 E92000001 2017 55660155 2 E92000001 2018 56115027 3 E92000001 2019 56568795 4 E92000001 2020 57019007

```

Extrapolate MYE using SNPP and NPP data

Single Area

Construct aggregate data for Exeter from 2011-2065:

• use MYE data up to 2016, aggregated by age and gender.
• then use SNPP data up to 2041, aggregated by age and gender.
• extrapolate using NPP data and Exeter's (2041) age-gender structure.
• aggregrate the extrapolated data by age and gender
• plot the data.

Source Code

Bulk Calculation

In this example we extrapolate and aggregrate the SNPP for every LAD in Wales:

• for each area,
  • extrapolate from 2039 to 2050 using the 2039 age-gender structure.
  • aggregate the extrapolated datma by age and gender.
  • append to full dataset.
• save Wales dataset as csv:

| GEOGRAPHYCODE | PROJECTEDYEARNAME | OBSVALUE | | -------------- | ------------------- | --------- | | W06000011 | 2040 | 262903.24103359133 | | W06000011 | 2041 | 262933.2340468692 | | W06000011 | 2042 | 263162.3661643687 | | W06000011 | 2043 | 263332.96819104964 | | W06000011 | 2044 | 263593.29826455784 | | W06000011 | 2045 | 263923.03553008236 | | W06000011 | 2046 | 264243.6253810904 | | W06000011 | 2047 | 264168.2113917932 | | W06000011 | 2048 | 264211.4576059673 | | ... | ... | ... |

Source Code

Construct an SNPP variant by applying NPP variant to a specific LAD

Here we apply the "hhh" (high growth) and "lll" (low growth) NPP variants to the SNPP data for Newcastle:

• calculate the principal ("ppp") projection by simply aggregrating the SNPP data for Newcastle, 2018-2039, by age and gender.
• calculate the variants by weighting the unaggregated data (i.e. by age and gender) by the ratio of the NPP variant/principal.
• aggregrate the variant data by age and gender.
• plot the results.

Source Code

Extrapolating an SNPP variant

Here we build on the examples above by not only applying the NPP variant, but extrapolating too. The process first involves extrapolating the SNPP by the NPP principal variant. The extrapolated data then has the variant adjustments applied to it.

Source Code

Comparing household and population projections for a single LAD

In this example we simply plot the aggregate household projections for Newcastle against the (principal) population projection. You can see that population growth starts to tail off more than the household growth. This suggests a decrease in household size. Further inspection of the data should confirm this.

Source Code

Code Documentation

Package documentation can be viewed like so:

python import ukpopulation.myedata as MYEData help(MYEData) import ukpopulation.nppdata as NPPData help(NPPData) import ukpopulation.snppdata as SNPPData help(SNPPData) import ukpopulation.snhpdata as SNHPData help(SNHPData)

Contributions

Contributions to this package are welcomed via the usual pull request mechanism.

Support

If you encounter a bug, feel the documentation is incorrect or incomplete, or want to suggest new features, please post an issue in the issues tab.

Citing

Please acknowledge this software if you use it in your work:

bibtex @software{neworder, doi = { 10.5281/zenodo.4244147 }, author = { Andrew P Smith, Tom Russell }, year = { 2020 }, version = { 1.2.2 }, url = { https://github.com/nismod/ukpopulation }, title = { ukpopulation: UK Demographic Projections } }

Acknowledgements

This package was developed as a component of the EPSRC-funded MISTRAL programme, part of the Infrastructure Transitions Research Consortium.