[R-sig-Geo] specifying time period for splm

[Tim Meehan]

Hi Maryia,

I think you are on the right track.  From the JSS paper (page 3), your data
can be:

1. A data.frame whose first two variables (columns) are the individual and
time indexes. The data should be sorted by individual (Spatial Unit) and
then time (Year), like you have it.  In this case the index argument in the
call to spml should be left to the default value, which it is in your
example.  Note that it isn't clear in your example if the first column
(with Spatial Unit 1) is an actual column in the dataframe or the row
names.  If it is row names, then you can make it a column with
'yourdata$Unit <- row.names(yourdata)', and then move it to the first
column with 'yourdata <- yourdata[,c(4,1,2,3)]'.

The other option is:
ˆ
2. A data.frame and a character vector indicating the indexes variables.
In this case, the indices wouldn't be the first two columns.  They would be
somewhere else in the dataframe.  But you would specify the columns in the
call to spml by adding something like 'index=c("Unit", "Year")'.  But, even
in this case, I would presort the dataframe by Unit and Year to be safe.

One thing that I think is important:

When you import the shapefile to make weights, there is a good chance that
the shapes won't be sorted according to the spatial units column in your
dataset.  That is, the first shape might not actually be Spatial Unit 1,
like in you sorted data from above.  To check, you can create a
SpatialPolygonDataFrame called, say, 'spdf1' and then run something like
'plot(spdf1[1])' to see if R plots Spatial Unit 1 or something else.  If
the shape order is different, you should reorder your
SpatialPolygonDataFrame after creating it from the shapefile but before
making weights.  If this is the case, let me know and I can send along a
code chunk to do this.

Best,
Tim


On Wed, Jan 6, 2016 at 8:58 PM, Maryia Bakhtsiyarava <bakht013 at umn.edu>
wrote:

> Hello,
>
> I would be very thankful for any help with my issue. I am relatively new to
> R and would greatly appreciate your help.
>
> I am trying to run spatial panel data models using the "splm," package. I
> studied the manual and have been closely following the article by G. Millo
> and G. Piras in the Journal of Statistical Software titled "splm: Spatial
> Panel Data Models in R" to create my own models. What I don't seem to
> understand is how R understands that the data are arranged in time series..
> I have repeated observations for spatial units for 5 years, however, I have
> not found where in the script I need to specify the periods. I looked at
> the data Millo used in the article, and even though the data are arranged
> by years, there is no explicit mention in the code or article of how to
> pass the time periods to R.
>
> Let's assume I have the following:
> I construct a spatial weights matrix (sp_weightsm) from the shapefile of my
> spatial units.
> my formula is: fm1<-y~x1+x2+x3
> mod1<-spml(formula = fm2, data = sids, index=NULL, listw=sp_weightsm,
> lag=TRUE, spatial.error = "b", model = "within", effect = "individual",
> method = "eigen", na.action = na.fail, quiet = TRUE, zero.policy = NULL,
> tot.solve = 1e-10, control=list(), legacy=FALSE)
>
> my data has the following structure:
>                         Year   X1   X2
> Spatial Unit 1  2000   ....   .....
> Spatial Unit 1  2001
> Spatial Unit 2  2000
> Spatial Unit 2  2001
> Spatial Unit n  .....
>
> This model runs without errors however I am pretty sure the results are not
> meaningful because how would R know the time periods?
> So, my question is: How do I pass on the time periods to R? Do I need to
> subset my dataset into different parts based on years?
>
> Thank you in advance,
> Maria
>
>         [[alternative HTML version deleted]]
>
> _______________________________________________
> R-sig-Geo mailing list
> R-sig-Geo at r-project.org
> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>

	[[alternative HTML version deleted]]