[R-sig-Geo] Location level analysis of spatio-temporal data

[Roger Bivand]

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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 <saiku1 at umbc.edu> 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
>>
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>>
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-- 
Roger Bivand
Department of Economics, Norwegian School of Economics,
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