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![Page 1: Exploring the direct rebound effect: systematic relationships between model robustness and coefficient estimates Lee Stapleton, Steve Sorrell, Tim Schwanen.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649e245503460f94b1209c/html5/thumbnails/1.jpg)
Exploring the direct rebound effect: systematic relationships between model robustness and coefficient estimates
Lee Stapleton, Steve Sorrell, Tim Schwanen
![Page 2: Exploring the direct rebound effect: systematic relationships between model robustness and coefficient estimates Lee Stapleton, Steve Sorrell, Tim Schwanen.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649e245503460f94b1209c/html5/thumbnails/2.jpg)
I was last at the 2007 incarnation of this conference in Chennai…
![Page 3: Exploring the direct rebound effect: systematic relationships between model robustness and coefficient estimates Lee Stapleton, Steve Sorrell, Tim Schwanen.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649e245503460f94b1209c/html5/thumbnails/3.jpg)
Contents
• Headline Summary
• Context
• Methods
• Results
• Implications
![Page 4: Exploring the direct rebound effect: systematic relationships between model robustness and coefficient estimates Lee Stapleton, Steve Sorrell, Tim Schwanen.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649e245503460f94b1209c/html5/thumbnails/4.jpg)
Headline Summary
• Rebound estimates vary from 10.6% to 26.8% (average = 18.1%)• The estimates are higher when the models are
more robust in a statistical sense• The estimated effects of other variables (e.g.
income and oil price shocks) also depend on model robustness• The correlations between coefficient size and
robustness may have implications for modelling beyond our study
![Page 5: Exploring the direct rebound effect: systematic relationships between model robustness and coefficient estimates Lee Stapleton, Steve Sorrell, Tim Schwanen.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649e245503460f94b1209c/html5/thumbnails/5.jpg)
• Technical improvements lower transport costs and thereby encourage increased transport activity and energy use
• Passengers travel further and more often in larger, faster, more powerful and emptier cars
• But establishing causality is difficult when (i) data are limited and uncertain (ii) data exhibit limited change over time (near horizontal lines in geometric terms); (iii) appropriate regression methods are complicated to implement
Context
![Page 6: Exploring the direct rebound effect: systematic relationships between model robustness and coefficient estimates Lee Stapleton, Steve Sorrell, Tim Schwanen.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649e245503460f94b1209c/html5/thumbnails/6.jpg)
Methods – data I
![Page 7: Exploring the direct rebound effect: systematic relationships between model robustness and coefficient estimates Lee Stapleton, Steve Sorrell, Tim Schwanen.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649e245503460f94b1209c/html5/thumbnails/7.jpg)
Methods – data II
![Page 8: Exploring the direct rebound effect: systematic relationships between model robustness and coefficient estimates Lee Stapleton, Steve Sorrell, Tim Schwanen.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649e245503460f94b1209c/html5/thumbnails/8.jpg)
Methods – modelling rebound • Approach one: how does improved technical
efficiency (declining vehicle fuel intensity and declining fuel prices) increase how far people travel (vehicle kilometres travelled - VKM)?
• Approach two: how does improved technical efficiency (declining fuel costs) increase how far people travel (vehicle kilometres travelled - VKM)?
![Page 9: Exploring the direct rebound effect: systematic relationships between model robustness and coefficient estimates Lee Stapleton, Steve Sorrell, Tim Schwanen.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649e245503460f94b1209c/html5/thumbnails/9.jpg)
Methods – model types • Static regression models: quantify the change in
car travel over time attributable to different variables (rebound variables, income, urbanisation and congestion and oil price shocks)• Dynamic regression models: acknowledge that
car travel in any particular year is partly dependent on car travel in previous years• Co-integrating regression models: in effect, these
are similar to static regression models but (may be) optimal for ‘trending’ variables
![Page 10: Exploring the direct rebound effect: systematic relationships between model robustness and coefficient estimates Lee Stapleton, Steve Sorrell, Tim Schwanen.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649e245503460f94b1209c/html5/thumbnails/10.jpg)
Methods – how many models?
27 models take rebound Approach A
27 models take rebound Approach B
24 static models
24 dynamic models
6 co-integrating models
54 final models
![Page 11: Exploring the direct rebound effect: systematic relationships between model robustness and coefficient estimates Lee Stapleton, Steve Sorrell, Tim Schwanen.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649e245503460f94b1209c/html5/thumbnails/11.jpg)
Methods – diagnostics (static and dynamic models)
• Coefficients: do they behave? [2 tests]• Residuals: do they behave? [3 tests] • Stability: are predictions stable? [2 tests] • Parsimony: is their a sound balance between good
predictions and model complexity? [3 tests]• Functional form: is the model structure
appropriate? [2 tests]
48 MODELS x 12 DIAGNOSTIC TESTS = 576 TESTS ON STATIC AND DYNAMIC MODELS
![Page 12: Exploring the direct rebound effect: systematic relationships between model robustness and coefficient estimates Lee Stapleton, Steve Sorrell, Tim Schwanen.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649e245503460f94b1209c/html5/thumbnails/12.jpg)
Methods – diagnostics (co-integrating models)
• Coefficients: do they behave? [2 tests]
• Residuals: do they behave? [1 test]
• Stability: are predictions stable? [1 test]
• Goodness of fit: how well does the model match the data? [1 test]
6 MODELS x 5 DIAGNOSTIC TESTS = 30 TESTS ON CO-INTEGRATING MODELS
![Page 13: Exploring the direct rebound effect: systematic relationships between model robustness and coefficient estimates Lee Stapleton, Steve Sorrell, Tim Schwanen.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649e245503460f94b1209c/html5/thumbnails/13.jpg)
Methods - robustness
![Page 14: Exploring the direct rebound effect: systematic relationships between model robustness and coefficient estimates Lee Stapleton, Steve Sorrell, Tim Schwanen.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649e245503460f94b1209c/html5/thumbnails/14.jpg)
Methods – robustness composites I
Robustness (health / strength)
![Page 15: Exploring the direct rebound effect: systematic relationships between model robustness and coefficient estimates Lee Stapleton, Steve Sorrell, Tim Schwanen.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649e245503460f94b1209c/html5/thumbnails/15.jpg)
Methods – robustness composites II
Coefficients Standard Stability Parsimony Functional Form
Measure
A
Measure
B Measure
A
Measure
B
Measure
C
Measure
A
Measure
B
Measure A
Measure B
Meas
ure C
Measure A
Measure
B
2 points
2 points
2 points
1 point
1 point
2 points
2 points
1 point
1 point
1 point
2 points
2 points
Coefficients Standard Stability Goodness of fit
Measure A
Measure B Measu
re A
Measure A
Measure
A
2 points
2 points
1 point
2 points
1 point
Static and dynamic models
Co-integrating models
![Page 16: Exploring the direct rebound effect: systematic relationships between model robustness and coefficient estimates Lee Stapleton, Steve Sorrell, Tim Schwanen.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649e245503460f94b1209c/html5/thumbnails/16.jpg)
Results – rebound (long run)
n = 28
= complex robustness
= simple robustness
Systematic - SATURATING
![Page 17: Exploring the direct rebound effect: systematic relationships between model robustness and coefficient estimates Lee Stapleton, Steve Sorrell, Tim Schwanen.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649e245503460f94b1209c/html5/thumbnails/17.jpg)
Results – oil price dummy
Systematic – LINEAR
n = 22
= complex robustness
= simple robustness
![Page 18: Exploring the direct rebound effect: systematic relationships between model robustness and coefficient estimates Lee Stapleton, Steve Sorrell, Tim Schwanen.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649e245503460f94b1209c/html5/thumbnails/18.jpg)
Results - other
![Page 19: Exploring the direct rebound effect: systematic relationships between model robustness and coefficient estimates Lee Stapleton, Steve Sorrell, Tim Schwanen.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649e245503460f94b1209c/html5/thumbnails/19.jpg)
Implications - rebound• The size of the long run direct rebound effect for
personal automotive travel in Great Britain suggested by our results (range = 10.6% - 26.8%; mean = 18.1%) accords well with previous studies which have attempted to measure this particular rebound effect in other country contexts.
• However, the aggregate rebound effect (including direct, indirect and economy wide components) is more important yet extremely difficult to quantify unacceptable levels of uncertainty.
![Page 20: Exploring the direct rebound effect: systematic relationships between model robustness and coefficient estimates Lee Stapleton, Steve Sorrell, Tim Schwanen.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649e245503460f94b1209c/html5/thumbnails/20.jpg)
Implications -methods
• Calls into question the extent to which we understand different phenomena where that understanding is predicated upon the application of explicit methodologies (as, possibly, opposed to theoretical and tacit understandings of phenomena)
• Is this a first step towards the construction of true coefficients / outcomes / results?
![Page 21: Exploring the direct rebound effect: systematic relationships between model robustness and coefficient estimates Lee Stapleton, Steve Sorrell, Tim Schwanen.](https://reader035.fdocuments.us/reader035/viewer/2022081519/56649e245503460f94b1209c/html5/thumbnails/21.jpg)
Thanks!