This is the `plot`

method for the class `"bermantest"`

.
An object of this class represents the outcome of Berman's test
of goodness-of-fit of a spatial Poisson point process model,
computed by `berman.test`

.

For the *Z1* test (i.e. if `x`

was computed using
`berman.test( ,which="Z1")`

),
the plot displays the two cumulative distribution functions
that are compared by the test: namely the empirical cumulative distribution
function of the covariate at the data points, \(\hat F\),
and the predicted
cumulative distribution function of the covariate under the model,
\(F_0\), both plotted against the value of the covariate.
Two vertical lines show the mean values of these two distributions.
If the model is correct, the two curves should be close; the test is
based on comparing the two vertical lines.

For the *Z2* test (i.e. if `x`

was computed using
`berman.test( ,which="Z2")`

), the plot displays the empirical
cumulative distribution function of the values
\(U_i = F_0(Y_i)\) where \(Y_i\) is the
value of the covariate at the \(i\)-th data point. The diagonal line
with equation \(y=x\) is also shown. Two vertical lines show the
mean of the values \(U_i\) and the value \(1/2\). If the
model is correct, the two curves should be close. The test is based on
comparing the two vertical lines.