1. International Workshop on Population Projections using Census Data
14 – 16 January 2013
Beijing, China

2. Session VI: Population projections for national populations
Tools for the preparation of national projections
Preparing the data and formulating assumptions
Dealing with uncertainty: variants and illustrative scenarios

3. Tools for the preparation of national projections
Overview

4. Tools for the preparation of national projections
Spectrum (Futures Institute)
RUPEX (US Census Bureau)
MORTPAK (UN Population Division)
LIPRO (NIDI)
PEDA (IIASA)

5. Tools for the preparation of national projections: Newcomer
ProFamy (China)
PADIS (China)
PPPD (Uni Rostock)
MICMAC (Europe)

6. Preparing the data and formulating assumptions
Before a projection can be produced, data need to be collected, analyzed and, if necessary, adjusted (see previous Sessions)
It is important to also collect time series of demographic data in order to have a sound basis for the formulation of projection assumptions.

7. Preparing the data and formulating assumptions
As minimum, the following data need to at hand:
Population by age and sex for the base year (start year, jump-off year)
Age specific fertility data for the period immediately before the base year
Age specific mortality data (or life tables) for the period immediately before the base year.
Total net migration for the period immediately before the base year, by age and sex if possible.

8. Preparing the data and formulating assumptions
Based on the data available, assumptions for fertility, mortality and net migration need to be formulated.
In order to account for uncertainty, variant assumptions may be formulated.
The tools presented in Sessions IV and V can be sued to calculate future trends of fertility, mortality and migration.

9. Preparing the data and formulating assumptions
The data prepared need to be entered into a projection software.
The steps to enter and carry out projections are shown in the follwoing.

10. Using Spectrum
SPECTRUM is a suite of easy to use policy models which provide policymakers with an analytical tool to support the decision making process.
SPECTRUM consists of several software models including:
DemProj: Demography
FamPlan: Family Planning
LiST: Lives Saved Tool (Child Survival)
AIM: AIDS Impact Model
Goals: Cost and impact of HIV Intervention
Resource Needs Module: Costs of implementing an HIV/AIDS program
RAPID: Resources for the Awareness of Population Impacts on Development
Safe Motherhood Model
Allocate

11. Using Spectrum SPECTRUM is at version 4.51.
As it is under continuing development, one should check for updates online:

12. Using Spectrum

13. Spectrum

14. Using Spectrum Advantages: Disadvantages Reliable and well tested
Appealing user-interface
User base is large, but concentrated among health and policy professionals (UNAIDS)
Support, on-site Training available
Disadvantages
Complex package due to integration into a variety of other tools (AIDS, POLICY etc.)
Obtaining results can be cumbersome

15. Using Spectrum Steps: 1. Projection parameter settings 2. Data input
3. Executing the projection
4. Obtaining, saving the results

16. Preparing the data and formulating assumptions
Overview

17. Hands-on exercise: Preparing a cohort-component projection with Spectrum

18. Hands-on exercise
Executing the sample projection and examining the results
Preparing a new projection
Adding data
Obtaining results from Excel

19. Using Spectrum 1
Sample.pjn

20. Using Spectrum 2

21. Using Spectrum 3
Projection menu group

22. Using Spectrum 4
Set last year
Uncheck AIDS

23. Using Spectrum 5

24. Using Spectrum 6

25. Using Spectrum 7

26. Using Spectrum 8

27. Using Spectrum 9

28. Using Spectrum 10

29. Using Spectrum 11

30. Using Spectrum 12

31. Using Spectrum13

32. Using Spectrum 14

33. Using Spectrum 15
Spectrum stores results in files with the extension *.dp
By renaming the file to *.csv, it can directly be opened by Excel

34. Dealing with uncertainty: variants and illustrative scenarios
Overview

35. Dealing with uncertainty: variants and illustrative scenarios
Population projections are constraint by the imperfect knowledge of current and future demographic settings and trends. Although the demographic momentum inherent in demographic dynamics has allowed demographers to produce demographic projection with a comparatively high quality, it is impossible to make a perfect projection.

36. Dealing with uncertainty: variants and illustrative scenarios
A traditional and well accepted way to incorporate uncertainty into population projections is the preparation of projections variants that show a certain range of results that is deemed plausible.
Another, more recent approach is using the ubiquitous computer power of modern computing equipment to create probabilistic projections consisting of many possible demographic pathways. It should be noted that the probabilistic approach is still a field under development.

37. Dealing with uncertainty: variants and illustrative scenarios
Scenarios are yet another way to illustrate future demographic trends. Scenarios are created by describing a future in a qualitative way, and then constructing corresponding demographic trends. Scenarios are then the answer to a “What if?” question

38. Dealing with uncertainty: variants and illustrative scenarios
Common scenarios
Constant fertility
Constant Mortality
No migration
Instant replacement

39. Preparing and comparing different projection variants
Hands-on exercise:
Preparing and comparing different projection variants

40. Hands-on exercise: Scenarios
Spectrum: Comparison Projections
Start by creating a Projection, using data in Spectrum.
You may modify the data as you wish: Set fertility to constant, for example
Or simply use the medium variant available in Spectrum as a starting point. Name it UgandaMedium.
Select an appropriate base year (2010?).
Select an appropriate last year (2050?)
Inspect the settings. Save the projection
Next add more scenarios.

41. Hands-on exercise: Scenarios
Add another scenarios.
You could just create another projection input file, apply your scenario setting and save it with an appropriate name.
There is a shortcut: Open the file you just saved again. Spectrum gives you a choice. Click on Load and rename.

42. Hands-on exercise: Scenarios
We want the second scenario to keep fertility levels constant at base level. Name the second scenario UgandaConstant.
Spectrum has now two projections loaded: UgandaMedium and UgnadaConstant. UgandaConstant is right now only a copy of UgandaMedium, so we have to make changes to the fertility settings in UgandaConstant.
Make sure that UgandaConstant is set to be the active projection.

43. Hands-on exercise: Scenarios
In order to keep the fertility constant, you can either copy the base fertility to the projection years, or use Spectrum’s copy and duplicate functions:
Highlight the fertility and click Duplicate.
Check if the fertility has been changed: Go to results and look at the fertility chart.
Note that there are now two fertility trends, one named UgandaMedium, and one named UgandaConstant.

44. Hands-on exercise: Scenarios
Now you may add even more scenarios.
As the first scenario (UgandaMedium) is the reference scenario, set UgandaMedium to be the active projection.
Now re-load UgandaMedium, and chose Load and rename.
Rename it to UgandaInstant.

45. Hands-on exercise: Scenarios
What do the scenarios reveal about the demographic future of the country chosen?
Discuss the results.

46. Evaluation of projection results
Projections are about the future, and therefore are invariably incorrect. It would not be useful to evaluate them in terms of their correctness (accuracy). Instead, one should assess them differently:
Sound Methodology
The projection makes sense relative to the characteristics and assumptions of the methods
Internal Consistency
The projection makes sense compared to historical demographic patterns
The projection makes sense compared to local socioeconomic/ cultural characteristics
External Consistency
The projection makes sense compared to contextual and/or comparison areas

47. Lab time Create a new projection using your own data.
Hint: You may use the projection available in Spectrum and change only those indicators you have data for.

48. Thank you