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Time series.

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Presentation on theme: "Time series."— Presentation transcript:

1 Time series

2 Comments of a trivial or wildly speculative nature are not acceptable.
More than generic, learned responses are required.

3 Relevance of forecast Relate the results to the context, eg reference made to whom it is useful for - economic planners or individual business. Could include reference to changes in conditions.

4 Relevance of forecast There could be a problem in extrapolating too far especially where non linear models have been applied.

5 Relevance of forecast Comment on conditions remaining constant over the period of the extrapolation related to the context can be of significance.

6 Features of the data Discussion of curvature, seasonal effects, linearity, outliers, ramps etc where appropriate.

7 Features of the data Adjacent periods may be compared once the data has been seasonally adjusted. Longitudinal trends over consecutive periods of time is what is important.

8 Appropriateness of the model.
The decision should be primarily visual. Basing a decision on the appropriateness of the model on the R2 value alone is not appropriate.

9 Appropriateness of the model.
Consideration of the model could include reference to additive, multiplicative, steps, ramps and giving reasons why – this needs to be a comment related to the smoothed data.

10 Appropriateness of the model.
Over plot of data discussed.

11 Improvements to the model (not data collection method.)
A polynomial, log or exponential model for a trend is rarely appropriate when related to a long run or unlimited time (over a limited period).

12 Improvements to the model (not data collection method.)
Weighting towards the end of period in which the data is collected could improve the model.

13 Seasonally adjusted data
Discussion involving interpretation of seasonally adjusted values should be related to seasonal adjustment enabling trend over consecutive time periods to be seen

14 Seasonally adjusted data
You must consider that you do not need to comment on all aspects. Don’t try and end up giving contradictions

15 Comment You must consider that you do not need to comment on all aspects. Don’t try and end up giving contradictions.


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