On 14.07.2015 09:51, Johannes Lips wrote:
On 11.07.2015 17:35, Joshua Ulrich wrote:
On Fri, Jul 10, 2015 at 5:01 AM, Johannes Lips
<johannes.l...@gmail.com> wrote:
Dear list,
I have implemented the test from Lee and Strazichich (2003, 2004) in
R and
uploaded it to github. [1]
The advantage of this test is, that it endogenously determines the
dates of
up to two possible structural breaks and
it includes these structural breaks under the null and also the
alternative
hypothesis.
I also implemented a General-to-Specific Approach to determine the
number of
lagged augmented terms to include in the test equation.
At the moment it's not very efficient in regard to computing time, so I
would be glad if someone could point out improvements to make the code
faster and more efficient.
If you provide an example I can run, I can profile it to look for
bottlenecks. From a quick look at the code, one thing that should
help a fair amount is to avoid calls to lm() and call lm.fit()
directly.
I've implemented the use of lm.fit() instead of lm in a first function
call, where I only need the residuals of the OLS.
In all other instances it is a bit harder to replace, because I need
the t-statistics and those are not as easily accessible from lm.fit()
as from lm.
I need to check if the lm.fit() call really is equivalent to the lm
call, because I think the results slightly changed, but the time gain
was already considerable. It went from 3.6h to 2h on nearly 3000
observations, just by replacing the lm with lm.fit() in two places.
Thanks again,
johannes
Hi all,
so I've managed to replace lm() with lm.fit() in all instances and made
the lm() call only available to get the results for the breakpoints.
This results in a reduction of the runtime to roughly a third of the
original runtime. So thanks a lot for this very valuable suggestion.
I yesterday uploaded the final code to my github repository. [1] So
please, if you find obvious mistakes or problems, just let me know.
Best regards,
johannes
[1] https://github.com/hannes101/LeeStrazicichUnitRoot
Thanks in advance!
Best regards,
Johannes Lips
[1] https://github.com/hannes101/LeeStrazicichUnitRoot
Lee, Junsoo and Mark C. Strazicich (2003). “Minimum Lagrange
Multiplier Unit
Root Test with Two Structural Breaks”. In: The Review of Economics and
Statistics 85.4, pp. 1082–1089.
Lee, Junsoo and Mark C. Strazicich (2004). “Minimum LM Unit Root
Test with
One Structural Break”. In: 04-17. url:
https://ideas.repec.org/p/apl/wpaper/04-17.html (visited on
02/04/2015).
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