runsNAltraj {adehabitatLT}  R Documentation 
runsNAltraj
performs a runs test to detect any autocorrelation
in the location of missing relocations, for each burst of an object of
class ltraj
.
summaryNAltraj
returns a summary of the number and proportion
of missing values for each burst of an object of class
ltraj
.
plotNAltraj
plots the missing values in an object of class
ltraj
against the time.
runsNAltraj(x, nrep = 500, plotit = TRUE, ...) summaryNAltraj(x) plotNAltraj(x, ...)
x 
An object of class 
nrep 
Number of randomisations 
plotit 
logical. Whether the results should be plotted on a graph 
... 
Further arguments to be passed to the generic function

The statistics used here for the test is the number of runs in the sequence of relocations. For example, the sequence relocNANArelocrelocrelocNANANAreloc contains 5 runs, 3 runs of successful relocations and 2 runs of missing values. Under the hypothesis of random distribution of the missing values in the sequence, the theoretical expectation and standard deviation of the number of runs is known. The runs test is a randomization test that compares the standardized value of the number of runs (i.e. (valueexpectation)/(standard deviation)) to the distribution of values obtained after randomizing the distribution of the NA in the sequence. Thus, a negative value of this standardized number of runs indicates that the missing values tend to be clustered together in the sequence.
runsNAltraj
returns a list of objects of class
randtest
(if a burst does not contain any missing value, the
corresponding component is NULL).
In the versions of adehabitatLT prior to 0.3.21, a bug occurred in the calculation of the Pvalue (the test actually presented the value 1P). This bug is now corrected.
Clement Calenge clement.calenge@ofb.gouv.fr
ltraj
for additional information about objects of
class ltraj
, setNA
for additional information
about missing values in such objects
## Two relocations are theoretically separated by ## 10 minutes (600 seconds) data(puechcirc) puechcirc ## plot the missing values plotNAltraj(puechcirc) ## Test for an autocorrelation pattern in the missing values (runsNAltraj(puechcirc))