History of LOTUS release 
=========================

  LOTUS 2.3
---------------
    September 28, 2005 update

    1. Included an option to set the maximum number of regressors used in the node models for
       the stepwise model option.

    2. Corrected a bug in the generation of the subtrees seqeuence for pruning.

    3. For stepwise option, a parent node is declared terminal if one or more of its child 
       node models contain only the intercept term.

    4. Corrected a bug in the computation of the Score and Wald statistics in stepwise 
       variable selection.

  LOTUS 2.2
---------------
    June 14, 2005 update

    1. Included a stepwise variable selection procedure for multiple linear logistic model.
       It uses the score test for entry into the model and the Wald test for staying in the
       model (similar to the stepwise procedure used in SAS Proc Logistic). User can specify 
       the two significance levels for entry and for stay.

    2. Redefined cost for stepwise and multiple linear model when missing values are present.
       In the older versions, node cost = node model's deviance using nonmissing data. In 
       current version, cost = node model's deviance using all data at the node with mean 
       imputation for missing values.

    3. Surrogate model is only used, in the presence of missing values, to estimate p when 
       the model is convergent. Otherwise, the best simple model with mean imputation for
       missing values is used.

  LOTUS 2.1
---------------
    October 18, 2004 update

    1. Included a test of significance of "H0: constant model vs H1:best simple model"
       at each node of the best simple linear option. Using the critical value 
       (default = 2) provided by user, a constant model is preferred if the absolute
       value of the Wald Statistics of most significant predictor is less than or
       equal to the user-specified critical value. 
    2. For the latex tree, if constant model is fitted to a terminal node, no predictor
       is printed beneath the node.

  LOTUS 2.0
---------------
    July 8, 2004 update

    1. Set the maximum number of terminal nodes in the maximal tree to be
                   tree_size = 500 + 500*(N/50000)    for LOTUS(S)
                   tree_size = 500 + 250*(N/50000)    for LOTUS(M)
       where N is the sample size.
    2. Corrected a bug in choosing the best simple linear model.
    3. Corrected a bug caused by floating overflows.
    4. For the latex tree with best simple linear option, a +/- sign is given 
       to indicate positive/negative slope.
    5. Included an option to create a new category for missing values in nominal 
       categorical variables automatically if needed.

  LOTUS 1.04
---------------
    May 27, 2004 update

    1. Corrected an error caused by diverging parameter estimates during Newton-
       Raphson iterations.
    2. Corrected an error caused by rounding-off errors during Newton-Raphson 
       iterations.

  LOTUS 1.03
---------------
    April 27, 2004 update

    1. Display LaTeX tree diagram in landscape format if it contains 10 or more 
       terminal nodes; otherwise portrait format is used.
    2. For best simple linear option, the LaTeX tree will show the predictor for 
       the selected simple model, in addition to the proportion of 0's and 1's 
       beneath each terminal node.

  LOTUS 1.02
---------------
    November 16, 2003 update

    1. Included the definitions of subroutines median() and mode() in subroutine 
       grow_tree().
    2. Truncate p-hat if it gets too close to 0 or 1. Specifically, if p-hat < e,
       set p-hat = e; if p-hat > (1-e), set p-hat = (1-e), where e = 1.0e-15. 

  LOTUS 1.01
---------------
    October 21, 2003 update

    1. When Newton-Raphson fails to converge at the root node due to quasi-
       separation of data, estimates from the last iteration are reported.
    2. Corrected a bug in the computation of MCLASS.

  LOTUS 1.00
---------------
    September 1, 2003