Changes in QUINT Version 1.2 (2016-4-21)
========================================

* quint() is now able to handle categorical variables as
candidate splitting variables. The R class of these variables
should be factor. The levels of the factof can be specified
as numeric values or labels. 

* quint.validate() is a new function with which the bias (i.e.
optimism) of a fitted (pruned) quint tree can be estimated. 
The procedure is based on bootstrapping and makes use of 
the treatment effects in the leaves of the tree. The function 
returns the mean estimated optimism for either the effect size
or the raw mean difference. It also returns the leaf info data
frame identical to the leaf info of the quint object used as
input, with the addition of an extra column. This extra column 
contains the bias-corrected treatment effect values for the leaf
with the largest and the smallest (i.e., largest negative)
treatment effect. An extended list of output is possible.

* predict.quint() is a new S3 function to make 
predictions with new data using a fitted quint tree 
object. Three types of predictions are possible, to be 
specified within the "type" argument of the function. 
If "type='class'" the treatment subgroup classes are predicted 
for every patient individually. If "type='matrix'" a matrix 
with the positions of every patient within the fitted tree 
is given (i.e., the leaf number and corresponding node). 
If "type='li'" a leaf info data frame similar to quint$li is 
returned with treatment effect values (d or diff) newly 
computed from the input data set. 

* prune.quint() has been adapted such that it can handle 
categorical variables.

* plot.quint() has been adapted such that it can make and
display categorical splits. 

* the leaf info output of a quint object (quint$li) now
displays either the effect size (d) with its standard error (se)
or the raw mean difference (diff) with its standard error. 
This depends on whether "es" or "dm" is specified as treatment
effect.

* the abovementioned change for the leaf info output has 
also been implemented in the summary.quint() output.

* the split info output of a quint object (quint$si) has an extra
column. The fourth column contains the numerical split points. 
These are also produced for nominal variables. A fiftth 
column has been added to display the 'true' split points,
such that the levels of a categorical variable that comprise a
split point are pasted after one another.

* the abovementioned change for the split info output has
also been implemented in the summary.quint() output. Furthermore
an additional check has been implemented for quint$si to avoid
conflicts with the dimension size of quint$si objects made 
with version 1.0.

* a bug regarding a sub function within quint() 
has been solved. This sub function made use of the Gamma(x) 
function. Gamma(x) cannot handle large numbers; as a
consequence a warning was given and in the leaf output the 
standard error values for the effect size (d) values were NA.
The implemented solution regards an approximation for computing
the standard error to be used when the sample sizes exceed
a certain value.

* quint.control() can now return an error when the criterion 
is misspecified (i.e., not "es" or "dm").

* The documentation has been updated. Help files for
the quint.validate() and predict.quint() functions have been
newly added. And a recently published paper has been added
to the package documentation.