2. Forecasting UK Ratings Numbers Proposed Methodology D. Glen & J. Dowden

3. 2 Background UK Officer data significantly improved Ratings information still limited New surveys will provide information on –stock of ratings by department, age, gender –data on ratings wastage rates

4. 3 The Proposed Model Based on the one developed for UK Officer Projections Essentially a stock model adjusted for entry and exit assumptions S - stock of ratings, E = entry rate, w = % of ratings of age i who leave

5. 4 Formula 64 S t+1 =  (E i t + 1 Fit)Fit) + (1 - w i ) i = 16

6. 5 Previous Performance

7. 6 Ratings Projections Scenario 1 –Entry a fixed proportion of existing stock (4%) –Wastage also 4% –Implies decline in numbers because of Age Profile –Two retirement ages - 65 or 57

8. 7 Scenario 1

9. 8 Scenario 2 Assume 100 new ratings per year aged 17- 20 Wastage rates –20 < 40 - 6% per year –40 + - 1% per year Two retirement ages - 65 or 57

10. 9 Scenario 2 (Age 65)

11. 10 Scenario 2 (Age 57)

12. 11 Scenario Comparisons Projections to 2010 sensitive to different assumptions about wastage/retirement Age 65 –Scenario 1 - fall of 7.7% –Scenario 2 - rise of 1.1% Age 57 –Scenario 1 - fall of 13.8% –Scenario 2 - rise of 1.4%

13. 12 Conclusions Scenario simulation suggests forecasts are sensitive to key assumptions Very important to obtain accurate wastage data if this model is to be employed Future work will involve calibrating the model with empirical wastage data from future surveys