Guidance from the GLA for choosing models in Witan to submit for the SRP

How do I produce a ‘standard’ set of population projections?

One hurdle that users have come across is that they weren’t sure how to set up the models to produce a standard set of outputs such as they would have received from the GLA.

The default options the GLA would generally recommend to use are the Housing-Linked model, the Capped Household Size variant and Standard Fertility fertility assumption (for more information on what these mean, have a look at this post). If in the past, you have found the ‘Alternate’ variant roll projections to be a better fit for your local authority, then using the Trend-based projection and the Standard Fertility setting will replicate this.

When uploading your development data in the template, the GLA would recommend making sure that data is included for all years, including estimated development for 2011-2014. If you don’t have alternative estimates for these years, the SHLAA template that can be downloaded from the system includes estimated completions from the London Development Database.

Who should run the population projections in Witan?

This is up to each authority to determine for themselves. However, the GLA expects and generally encourage nominated Demography contacts to take a lead on this activity.

• If you are unclear who is the Demography contact in your local authority, please let the GLA know and they’ll be happy to confirm.
• If you’d like to know who are registered users of the system, drop Mastodon C a line and they can tell you.
• If you are the nominated contact for your authority, but don’t feel confident in producing projections in Witan, please either Mastodon C or GLA know and we’ll be happy to assist.

GLA contact: Demography@london.gov.uk

Mastodon C contact: witan@mastodonc.com

Can I get roll projections without providing population projections?

If you have provided roll data, but are still struggling to create your population projections, the GLA can now produce a set of roll projections for you using their publicly available SHLAA-based projections. They still recommend producing your own projections that incorporate your most up to date development assumptions.

The GLA London-wide SHLAA based 2015 projections are now online

When working with demographics data it’s worth knowing when new London-wide population projections are available online for you own analysis.

So, if you missed it, a number of variants of the GLA 2015 round population projections have now been published onto the London datastore.

You can find them at the link below:

http://data.london.gov.uk/dataset/2015-round-population-projections

Handy links for first time Witan users

If you haven’t used Witan before, you’d be forgiven for wondering how you’re supposed to use it when coming to it for the first time.

This is doubly the case if you’re using Witan to generate the Ward population projection split-gender dataset needed for using the GLA’s School Roll Projection (SRP) service.

So, we’ve compiled a few links to help you when doing this:

Video walkthrough

Below is a 5 minute video walkthrough of using Witan for the first time, from signing in to generating a population projection for the SRP.

 

 

Step by step instructions with screenshots

If you prefer reading text and seeing screenshots instead of watching videos, we’ve put together a step by step guide at the link below

https://github.com/MastodonC/witan.docs/blob/master/GUIDE.md

Guidance on using different models inside Witan

If you’re not sure what the options mean when setting up a model to generate projections, we’ve published some guidance on what they mean below:

https://witanbulletin.wordpress.com/2016/03/21/a-brief-guide-to-choosing-your-models-in-witan/

SRP guidance from the GLA

If you’re not quite sure which model to choose, here is some guidance from the GLA:

https://witanbulletin.wordpress.com/2016/05/31/guidance-from-the-gla-on-choosing-models-for-the-srp-using-witan/

Getting extra help

If anything isn’t obvious to you, you can always ask for help when using Witan by either emailing witan@mastodonc.com, or clicking the blue circle with a question mark in the bottom right of the screen – this will put you straight through to the support team, who can help you answer any questions you have.

 

 

 

Births by ward in your projection output

A few Witan users have been asking about having births in the generated output when creating a projection on Witan.

This is not needed for the school roll projections, just a further output that may be useful when deciding what projections to use.

I’m pleased to say this is now available with every projection generated – when running a new projection there will now be a new file to download, giving you some output a bit like this:

How to get it

When you generate a projection on Witan there will be a new file available to download among your other files:

For old projections

If the last time you generated a projection was more than a few days ago, you’ll need to generate a new version of your projection, to see the new data file.

The fastest way to do this is to find the last input file you have, download it, then re-upload as a new file.

When you next generate the file, you’ll have your births by ward file there to download.

Let us know how you get on!