Location level analysis of spatio-temporal data

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Location level analysis of spatio-temporal data

Sai Kumar Popuri
Hi,

I am new to spatio-temporal analysis and trying to understand some basics.
Suppose I have a large spatio-temporal data. I can either fit an advanced
model with a spatio-temporal covariance structure or I could fit a time
series model at each location separately. When are these two approaches
similar? When is the second approach justified?

Thank you,
Sai

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Re: Location level analysis of spatio-temporal data

chris english-2
Sai,

There is something like take it from the end to the beginning and back, or
beginning to end and back to
the beginning and end and back, and ask yourself what does my data
recommend. The end is how I suppose you
generally anticipate analyzing/modeling the data, and the beginning being
your understanding of how the data
was collected and its vagaries.

If you sampled your data, say .60 in a train set and reduced each variable
to its quantile median
     quantile(your_data[[x]][, 'your_one_of_many_variables'], type =8)[[3]]
# without na.rm = TRUE anticipating running this through caret 'gbm'
and then examine influence of time as against space among your variables.

Space can be characterized in a lot of dimensions, and then you have time
which seems often to be like a sampling rate upon those
potentially many spatial characteristics, But give it a try anyway and find
if time isn't up there in position one or two in variable importance with
spatial variables after you run your data through gbm.

For further reading I would suggest the work of Emmanual Parzen and also
his work in collaboration with Subhadeep (Deep) Mukhopadhyay
on why quantile median might be your special friend.

As ever, I probably shouldn't comment as I know little and there are much
better informed scientists here. The interesting claim to be
wrestled from the Parzen/Mukhopadhyay material is that the data (that you
have) informs the sufficient statistics to be found and that specific
domain knowledge is not necessary to such. This, is the claim, is the power
of the quantile median analysis.

Does this relieve you of answering your question of whether to apply
spatio-temporal upon the whole set, or time series upon a sampling point;
hard to say but Parzen/Mukhopadhyay say, give me your data and I'll give
you your sufficient statistics. It will, I suspect, at the very least
confirm
or disprove the proposition that your data is spatio-temporal (since you
don't say what it is) as a received notion, which is a good starting point
in any case.

My thoughts,
Chris


On Sat, Apr 28, 2018 at 11:16 PM, Sai Kumar Popuri <[hidden email]> wrote:

> Hi,
>
> I am new to spatio-temporal analysis and trying to understand some basics.
> Suppose I have a large spatio-temporal data. I can either fit an advanced
> model with a spatio-temporal covariance structure or I could fit a time
> series model at each location separately. When are these two approaches
> similar? When is the second approach justified?
>
> Thank you,
> Sai
>
>         [[alternative HTML version deleted]]
>
> _______________________________________________
> R-sig-Geo mailing list
> [hidden email]
> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>

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Re: Location level analysis of spatio-temporal data

chris english-2
Geez Marilyn, I would have thought, given your proclivity for geospatial
statistics you'd pretty well know where I was,
within a mile and a second or two. I guess you can check with Sai, as you
popped up the moment I replied to him.
Sigh. What will I tell my wife?
Chris

On Sun, Apr 29, 2018 at 10:54 PM, Marilyn Dean <[hidden email]>
wrote:

> chris,  I'm not for anything too crazy I am Marilyn Dean and age is not
> too big of a deal {as long as you are handsome and respectful as long as
> you are a good guy . I just want to have a time if you know what I mean ;)
>
>
>  also, whats your location? whats the plan for first meet?|
>
> On Sun, 29 Apr 2018 at 08:51 PM, chris english <
> [hidden email]> wrote:
>
>>
>>
>>
>>

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Re: Location level analysis of spatio-temporal data

Roger Bivand
Administrator
In reply to this post by chris english-2
Please never respond to spamming on-list. All the R lists are under attack
from at least one possibly breached cloud email provider, where posters or
responders may receive spam on posting. Your local spam filter may catch
these, but because the origin is authenticated (not by us), your spam
filter may not work. See:

https://stat.ethz.ch/pipermail/r-help/2018-April/452613.html

for more details.

Roger Bivand
List admin.

On Mon, 30 Apr 2018, chris english wrote:

> Sai,
>
> There is something like take it from the end to the beginning and back, or
> beginning to end and back to
> the beginning and end and back, and ask yourself what does my data
> recommend. The end is how I suppose you
> generally anticipate analyzing/modeling the data, and the beginning being
> your understanding of how the data
> was collected and its vagaries.
>
> If you sampled your data, say .60 in a train set and reduced each variable
> to its quantile median
>     quantile(your_data[[x]][, 'your_one_of_many_variables'], type =8)[[3]]
> # without na.rm = TRUE anticipating running this through caret 'gbm'
> and then examine influence of time as against space among your variables.
>
> Space can be characterized in a lot of dimensions, and then you have time
> which seems often to be like a sampling rate upon those
> potentially many spatial characteristics, But give it a try anyway and find
> if time isn't up there in position one or two in variable importance with
> spatial variables after you run your data through gbm.
>
> For further reading I would suggest the work of Emmanual Parzen and also
> his work in collaboration with Subhadeep (Deep) Mukhopadhyay
> on why quantile median might be your special friend.
>
> As ever, I probably shouldn't comment as I know little and there are much
> better informed scientists here. The interesting claim to be
> wrestled from the Parzen/Mukhopadhyay material is that the data (that you
> have) informs the sufficient statistics to be found and that specific
> domain knowledge is not necessary to such. This, is the claim, is the power
> of the quantile median analysis.
>
> Does this relieve you of answering your question of whether to apply
> spatio-temporal upon the whole set, or time series upon a sampling point;
> hard to say but Parzen/Mukhopadhyay say, give me your data and I'll give
> you your sufficient statistics. It will, I suspect, at the very least
> confirm
> or disprove the proposition that your data is spatio-temporal (since you
> don't say what it is) as a received notion, which is a good starting point
> in any case.
>
> My thoughts,
> Chris
>
>
> On Sat, Apr 28, 2018 at 11:16 PM, Sai Kumar Popuri <[hidden email]> wrote:
>
>> Hi,
>>
>> I am new to spatio-temporal analysis and trying to understand some basics.
>> Suppose I have a large spatio-temporal data. I can either fit an advanced
>> model with a spatio-temporal covariance structure or I could fit a time
>> series model at each location separately. When are these two approaches
>> similar? When is the second approach justified?
>>
>> Thank you,
>> Sai
>>
>>         [[alternative HTML version deleted]]
>>
>> _______________________________________________
>> R-sig-Geo mailing list
>> [hidden email]
>> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>>
>
> [[alternative HTML version deleted]]
>
> _______________________________________________
> R-sig-Geo mailing list
> [hidden email]
> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>

--
Roger Bivand
Department of Economics, Norwegian School of Economics,
Helleveien 30, N-5045 Bergen, Norway.
voice: +47 55 95 93 55; e-mail: [hidden email]
http://orcid.org/0000-0003-2392-6140
https://scholar.google.no/citations?user=AWeghB0AAAAJ&hl=en

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