[R-sig-Geo] problem with enveloped test in spatstat

[Marcelino de la Cruz Rot]

Hi David,

This is very clearly explained in page 393 of Baddeley et al. 2015.

Basically, the MAD test is affected by transformations of the summary 
function, with the L-function providing more powerful tests because of 
its stabilization of the variance.

If you are interested in point pattern analysis I would recommend you to 
get a copy of this nice book.


Cheers,

Marcelino


Adrian Baddeley, Ege Rubak, Rolf Turner (2015). Spatial Point Patterns: 
Methodology and Applications with R. London: Chapman and
   Hall/CRC Press.
http://www.crcpress.com/Spatial-Point-Patterns-Methodology-and-Applications-with-R/Baddeley-Rubak-Turner/9781482210200/ 







El 21/04/2018 a las 18:05, David Unwin escribió:
> Can any *spatstat* user explain to me why the two p-values obtained below
> for an envelope test against CSR are so different?
>
>
>
>> data(swedishpines)
>> d<-swedishpines
>> plot(d)
>> mad.test(d,Kest,nsim=999,verbose=F)
>
>
>          Maximum absolute deviation test of CSR
>
>          Monte Carlo test based on 999 simulations
>
>          Summary function: K(r)
>
>          Reference function: theoretical
>
>          Alternative: two.sided
>
>          Interval of distance values: [0, 24] units (one unit = 0.1 metres)
>
>          Test statistic: Maximum absolute deviation
>
>          Deviation = observed minus theoretical
>
>
>
> data:  d
>
> mad = 150.69, rank = 216, p-value = *0.216*
>
>
>
>> mad.test(d,*Lest*,nsim=999,verbose=F)
>
>
>          Maximum absolute deviation test of CSR
>
>          Monte Carlo test based on 999 simulations
>
>          Summary function: L(r)
>
>          Reference function: theoretical
>
>          Alternative: two.sided
>
>          Interval of distance values: [0, 24] units (one unit = 0.1 metres)
>
>          Test statistic: Maximum absolute deviation
>
>          Deviation = observed minus theoretical
>
>
>
> data:  d
>
> mad = 2.9921, rank = 9, p-value = *0.009*
>
>
>
> *!!!*
>
>
>
> These data are dispersed relative to CSR:
>
>> kl<-envelope(d,Kest,nsim=999,correction="border")
>> plot(kl)
>
> Dave Unwin
>
> 	[[alternative HTML version deleted]]
>
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>

-- 
Marcelino de la Cruz Rot
Depto. de Biología y Geología
Física y Química Inorgánica
Universidad Rey Juan Carlos
Móstoles España