diff --git a/Makefile b/Makefile
index 80848649d..0715ec379 100644
--- a/Makefile
+++ b/Makefile
@@ -5,9 +5,9 @@ export LDFLAGS= -pthread -lm
 # add include path to Rinternals.h here
 
 ifeq ($(no_omp),1)
-	export CFLAGS = -Wall -O3 -msse2  -Wno-unknown-pragmas -DDISABLE_OPENMP 
+	export CFLAGS = -Wall -O3 -msse2  -Wno-unknown-pragmas -DDISABLE_OPENMP -funroll-loops 
 else
-	export CFLAGS = -Wall -O3 -msse2 -Wno-unknown-pragmas -fopenmp
+	export CFLAGS = -Wall -O3 -msse2 -Wno-unknown-pragmas -fopenmp  -funroll-loops 
 endif
 
 # expose these flags to R CMD SHLIB
@@ -18,11 +18,11 @@ BIN = xgboost
 OBJ = 
 SLIB = wrapper/libxgboostwrapper.so 
 RLIB = wrapper/libxgboostR.so 
-.PHONY: clean all R
+.PHONY: clean all R python
 
 all: $(BIN) wrapper/libxgboostwrapper.so
 R: wrapper/libxgboostR.so
-
+python: wrapper/libxgboostwrapper.so
 xgboost: src/xgboost_main.cpp src/io/io.cpp src/data.h src/tree/*.h src/tree/*.hpp src/gbm/*.h src/gbm/*.hpp src/utils/*.h src/learner/*.h src/learner/*.hpp 
 # now the wrapper takes in two files. io and wrapper part
 wrapper/libxgboostwrapper.so: wrapper/xgboost_wrapper.cpp src/io/io.cpp src/*.h src/*/*.hpp src/*/*.h
diff --git a/src/gbm/gbtree-inl.hpp b/src/gbm/gbtree-inl.hpp
index 2c48f501c..bd3adac08 100644
--- a/src/gbm/gbtree-inl.hpp
+++ b/src/gbm/gbtree-inl.hpp
@@ -117,17 +117,13 @@ class GBTree : public IGradBooster<FMatrix> {
     }
 
     std::vector<float> &preds = *out_preds;
-    preds.resize(0);
+    const size_t stride = info.num_row * mparam.num_output_group;
+    preds.resize(stride * (mparam.size_leaf_vector+1));
     // start collecting the prediction
     utils::IIterator<SparseBatch> *iter = fmat.RowIterator();
     iter->BeforeFirst();
     while (iter->Next()) {
       const SparseBatch &batch = iter->Value();
-      utils::Assert(batch.base_rowid * mparam.num_output_group == preds.size(),
-                    "base_rowid is not set correctly");
-      // output convention: nrow * k, where nrow is number of rows
-      // k is number of group
-      preds.resize(preds.size() + batch.size * mparam.num_output_group);
       // parallel over local batch
       const unsigned nsize = static_cast<unsigned>(batch.size);
       #pragma omp parallel for schedule(static)
@@ -135,13 +131,13 @@ class GBTree : public IGradBooster<FMatrix> {
         const int tid = omp_get_thread_num();
         tree::RegTree::FVec &feats = thread_temp[tid];
         int64_t ridx = static_cast<int64_t>(batch.base_rowid + i);
-        const unsigned root_idx = info.GetRoot(ridx);
+        utils::Assert(static_cast<size_t>(ridx) < info.num_row, "data row index exceed bound");
         // loop over output groups
         for (int gid = 0; gid < mparam.num_output_group; ++gid) {
-          preds[ridx * mparam.num_output_group + gid] =
-              this->Pred(batch[i],
-                         buffer_offset < 0 ? -1 : buffer_offset+ridx,
-                         gid, root_idx, &feats);
+          this->Pred(batch[i],
+                     buffer_offset < 0 ? -1 : buffer_offset + ridx,
+                     gid, info.GetRoot(ridx), &feats,
+                     &preds[ridx * mparam.num_output_group + gid], stride);
         }
       }
     }
@@ -211,24 +207,34 @@ class GBTree : public IGradBooster<FMatrix> {
     mparam.num_trees += tparam.num_parallel_tree;
   }
   // make a prediction for a single instance
-  inline float Pred(const SparseBatch::Inst &inst,
-                    int64_t buffer_index,
-                    int bst_group,
-                    unsigned root_index,
-                    tree::RegTree::FVec *p_feats) {
+  inline void Pred(const SparseBatch::Inst &inst,
+                   int64_t buffer_index,
+                   int bst_group,
+                   unsigned root_index,
+                   tree::RegTree::FVec *p_feats,
+                   float *out_pred, size_t stride) {
     size_t itop = 0;
     float  psum = 0.0f;
+    // sum of leaf vector 
+    std::vector<float> vec_psum(mparam.size_leaf_vector, 0.0f);
     const int64_t bid = mparam.BufferOffset(buffer_index, bst_group);
     // load buffered results if any
     if (bid >= 0) {
       itop = pred_counter[bid];
       psum = pred_buffer[bid];
+      for (int i = 0; i < mparam.size_leaf_vector; ++i) {
+        vec_psum[i] = pred_buffer[bid + i + 1];
+      }
     }
     if (itop != trees.size()) {
       p_feats->Fill(inst);
       for (size_t i = itop; i < trees.size(); ++i) {
         if (tree_info[i] == bst_group) {
-          psum += trees[i]->Predict(*p_feats, root_index);
+          int tid = trees[i]->GetLeafIndex(*p_feats, root_index);
+          psum += (*trees[i])[tid].leaf_value();
+          for (int j = 0; j < mparam.size_leaf_vector; ++j) {
+            vec_psum[j] += trees[i]->leafvec(tid)[j];
+          }
         }
       }
       p_feats->Drop(inst);
@@ -237,8 +243,14 @@ class GBTree : public IGradBooster<FMatrix> {
     if (bid >= 0) {
       pred_counter[bid] = static_cast<unsigned>(trees.size());
       pred_buffer[bid] = psum;
+      for (int i = 0; i < mparam.size_leaf_vector; ++i) {
+        pred_buffer[bid + i + 1] = vec_psum[i];
+      }
+    }
+    out_pred[0] = psum;
+    for (int i = 0; i < mparam.size_leaf_vector; ++i) {
+      out_pred[stride * (i + 1)] = vec_psum[i];
     }
-    return psum;
   }
   // --- data structure ---
   /*! \brief training parameters */
@@ -291,14 +303,17 @@ class GBTree : public IGradBooster<FMatrix> {
      *    suppose we have n instance and k group, output will be k*n 
      */
     int num_output_group;
+    /*! \brief size of leaf vector needed in tree */
+    int size_leaf_vector;
     /*! \brief reserved parameters */
-    int reserved[32];
+    int reserved[31];
     /*! \brief constructor */
     ModelParam(void) {
       num_trees = 0;
       num_roots = num_feature = 0;
       num_pbuffer = 0;
       num_output_group = 1;
+      size_leaf_vector = 0;
       memset(reserved, 0, sizeof(reserved));
     }
     /*!
@@ -311,10 +326,11 @@ class GBTree : public IGradBooster<FMatrix> {
       if (!strcmp("num_output_group", name)) num_output_group = atol(val);
       if (!strcmp("bst:num_roots", name)) num_roots = atoi(val);
       if (!strcmp("bst:num_feature", name)) num_feature = atoi(val);
+      if (!strcmp("bst:size_leaf_vector", name)) size_leaf_vector = atoi(val);
     }
     /*! \return size of prediction buffer actually needed */
     inline size_t PredBufferSize(void) const {
-      return num_output_group * num_pbuffer;
+      return num_output_group * num_pbuffer * (size_leaf_vector + 1);
     }
     /*! 
      * \brief get the buffer offset given a buffer index and group id  
@@ -323,7 +339,7 @@ class GBTree : public IGradBooster<FMatrix> {
     inline int64_t BufferOffset(int64_t buffer_index, int bst_group) const {
       if (buffer_index < 0) return -1;
       utils::Check(buffer_index < num_pbuffer, "buffer_index exceed num_pbuffer");
-      return buffer_index + num_pbuffer * bst_group;
+      return (buffer_index + num_pbuffer * bst_group) * (size_leaf_vector + 1);
     }
   };
   // training parameter
diff --git a/src/learner/evaluation-inl.hpp b/src/learner/evaluation-inl.hpp
index 0b207f4b9..50827b758 100644
--- a/src/learner/evaluation-inl.hpp
+++ b/src/learner/evaluation-inl.hpp
@@ -24,9 +24,10 @@ template<typename Derived>
 struct EvalEWiseBase : public IEvaluator {
   virtual float Eval(const std::vector<float> &preds,
                      const MetaInfo &info) const {
-    utils::Check(preds.size() == info.labels.size(),
+    utils::Check(info.labels.size() != 0, "label set cannot be empty");
+    utils::Check(preds.size() % info.labels.size() == 0,
                  "label and prediction size not match");
-    const unsigned ndata = static_cast<unsigned>(preds.size());
+    const unsigned ndata = static_cast<unsigned>(info.labels.size());
     float sum = 0.0, wsum = 0.0;
     #pragma omp parallel for reduction(+: sum, wsum) schedule(static)
     for (unsigned i = 0; i < ndata; ++i) {
@@ -99,6 +100,45 @@ struct EvalMatchError : public EvalEWiseBase<EvalMatchError> {
   }
 };
 
+/*! \brief ctest */
+struct EvalCTest: public IEvaluator {
+  EvalCTest(IEvaluator *base, const char *name)
+      : base_(base), name_(name) {}
+  virtual ~EvalCTest(void) {
+    delete base_;
+  }
+  virtual const char *Name(void) const {
+    return name_.c_str();
+  }
+  virtual float Eval(const std::vector<float> &preds,
+                     const MetaInfo &info) const {
+    utils::Check(preds.size() % info.labels.size() == 0,
+                 "label and prediction size not match");
+    size_t ngroup = preds.size() / info.labels.size() - 1;
+    const unsigned ndata = static_cast<unsigned>(info.labels.size());
+    utils::Check(ngroup > 1, "pred size does not meet requirement");
+    utils::Check(ndata == info.info.fold_index.size(), "need fold index");
+    double wsum = 0.0;
+    for (size_t k = 0; k < ngroup; ++k) {
+      std::vector<float> tpred;
+      MetaInfo tinfo;
+      for (unsigned i = 0; i < ndata; ++i) {
+        if (info.info.fold_index[i] == k) {
+          tpred.push_back(preds[i + (k + 1) * ndata]);
+          tinfo.labels.push_back(info.labels[i]);
+          tinfo.weights.push_back(info.GetWeight(i));
+        }        
+      }
+      wsum += base_->Eval(tpred, tinfo);
+    }
+    return wsum / ngroup;
+  }
+
+ private:
+  IEvaluator *base_;
+  std::string name_;
+};
+
 /*! \brief AMS: also records best threshold */
 struct EvalAMS : public IEvaluator {
  public:
@@ -109,7 +149,7 @@ struct EvalAMS : public IEvaluator {
   }
   virtual float Eval(const std::vector<float> &preds,
                      const MetaInfo &info) const {
-    const unsigned ndata = static_cast<unsigned>(preds.size());
+    const unsigned ndata = static_cast<unsigned>(info.labels.size());
     utils::Check(info.weights.size() == ndata, "we need weight to evaluate ams");
     std::vector< std::pair<float, unsigned> > rec(ndata);
 
@@ -206,10 +246,14 @@ struct EvalPrecisionRatio : public IEvaluator{
 struct EvalAuc : public IEvaluator {
   virtual float Eval(const std::vector<float> &preds,
                      const MetaInfo &info) const {
-    utils::Check(preds.size() == info.labels.size(), "label size predict size not match");
-    std::vector<unsigned> tgptr(2, 0); tgptr[1] = static_cast<unsigned>(preds.size());
+    utils::Check(info.labels.size() != 0, "label set cannot be empty");
+    utils::Check(preds.size() % info.labels.size() == 0,
+                 "label size predict size not match");
+    std::vector<unsigned> tgptr(2, 0); 
+    tgptr[1] = static_cast<unsigned>(info.labels.size());
+
     const std::vector<unsigned> &gptr = info.group_ptr.size() == 0 ? tgptr : info.group_ptr;
-    utils::Check(gptr.back() == preds.size(),
+    utils::Check(gptr.back() == info.labels.size(),
                  "EvalAuc: group structure must match number of prediction");
     const unsigned ngroup = static_cast<unsigned>(gptr.size() - 1);
     // sum statictis
diff --git a/src/learner/evaluation.h b/src/learner/evaluation.h
index d2134bfbd..90f4a5839 100644
--- a/src/learner/evaluation.h
+++ b/src/learner/evaluation.h
@@ -45,7 +45,9 @@ inline IEvaluator* CreateEvaluator(const char *name) {
   if (!strncmp(name, "pre@", 4)) return new EvalPrecision(name);
   if (!strncmp(name, "pratio@", 7)) return new EvalPrecisionRatio(name);
   if (!strncmp(name, "map", 3)) return new EvalMAP(name);
-  if (!strncmp(name, "ndcg", 3)) return new EvalNDCG(name);
+  if (!strncmp(name, "ndcg", 4)) return new EvalNDCG(name);
+  if (!strncmp(name, "ct-", 3)) return new EvalCTest(CreateEvaluator(name+3), name);
+
   utils::Error("unknown evaluation metric type: %s", name);
   return NULL;
 }
diff --git a/src/learner/objective-inl.hpp b/src/learner/objective-inl.hpp
index 7f7f08cc3..4b5b4f014 100644
--- a/src/learner/objective-inl.hpp
+++ b/src/learner/objective-inl.hpp
@@ -123,7 +123,7 @@ class RegLossObj : public IObjFunction{
       float p = loss.PredTransform(preds[i]);
       float w = info.GetWeight(j);
       if (info.labels[j] == 1.0f) w *= scale_pos_weight;
-      gpair[j] = bst_gpair(loss.FirstOrderGradient(p, info.labels[j]) * w,
+      gpair[i] = bst_gpair(loss.FirstOrderGradient(p, info.labels[j]) * w,
                            loss.SecondOrderGradient(p, info.labels[j]) * w);
     }
   }
diff --git a/src/tree/model.h b/src/tree/model.h
index af99a5145..f91e453f8 100644
--- a/src/tree/model.h
+++ b/src/tree/model.h
@@ -270,6 +270,7 @@ class TreeModel {
     param.num_nodes = param.num_roots;
     nodes.resize(param.num_nodes);
     stats.resize(param.num_nodes);
+    leaf_vector.resize(param.num_nodes * param.size_leaf_vector, 0.0f);
     for (int i = 0; i < param.num_nodes; i ++) {
       nodes[i].set_leaf(0.0f);
       nodes[i].set_parent(-1);
diff --git a/src/tree/param.h b/src/tree/param.h
index 5f02c065d..52c273749 100644
--- a/src/tree/param.h
+++ b/src/tree/param.h
@@ -22,10 +22,10 @@ struct TrainParam{
   //----- the rest parameters are less important ----
   // minimum amount of hessian(weight) allowed in a child
   float min_child_weight;
-  // weight decay parameter used to control leaf fitting
+  // L2 regularization factor
   float reg_lambda;
-  // reg method
-  int reg_method;
+  // L1 regularization factor
+  float reg_alpha;
   // default direction choice
   int default_direction;
   // whether we want to do subsample
@@ -36,6 +36,8 @@ struct TrainParam{
   float colsample_bytree;
   // speed optimization for dense column
   float opt_dense_col;
+  // leaf vector size
+  int size_leaf_vector;
   // number of threads to be used for tree construction,
   // if OpenMP is enabled, if equals 0, use system default
   int nthread;
@@ -45,13 +47,14 @@ struct TrainParam{
     min_child_weight = 1.0f;
     max_depth = 6;
     reg_lambda = 1.0f;
-    reg_method = 2;
+    reg_alpha = 0.0f;
     default_direction = 0;
     subsample = 1.0f;
     colsample_bytree = 1.0f;
     colsample_bylevel = 1.0f;
     opt_dense_col = 1.0f;
     nthread = 0;
+    size_leaf_vector = 0;
   }
   /*! 
    * \brief set parameters from outside 
@@ -63,15 +66,17 @@ struct TrainParam{
     if (!strcmp(name, "gamma")) min_split_loss = static_cast<float>(atof(val));
     if (!strcmp(name, "eta")) learning_rate = static_cast<float>(atof(val));
     if (!strcmp(name, "lambda")) reg_lambda = static_cast<float>(atof(val));
+    if (!strcmp(name, "alpha")) reg_alpha = static_cast<float>(atof(val));
     if (!strcmp(name, "learning_rate")) learning_rate = static_cast<float>(atof(val));
     if (!strcmp(name, "min_child_weight")) min_child_weight = static_cast<float>(atof(val));
     if (!strcmp(name, "min_split_loss")) min_split_loss = static_cast<float>(atof(val));
     if (!strcmp(name, "reg_lambda")) reg_lambda = static_cast<float>(atof(val));
-    if (!strcmp(name, "reg_method")) reg_method = atoi(val);
+    if (!strcmp(name, "reg_alpha")) reg_alpha = static_cast<float>(atof(val));
     if (!strcmp(name, "subsample")) subsample = static_cast<float>(atof(val));
     if (!strcmp(name, "colsample_bylevel")) colsample_bylevel = static_cast<float>(atof(val));
     if (!strcmp(name, "colsample_bytree")) colsample_bytree  = static_cast<float>(atof(val));
     if (!strcmp(name, "opt_dense_col")) opt_dense_col = static_cast<float>(atof(val));
+    if (!strcmp(name, "size_leaf_vector")) size_leaf_vector = atoi(val);
     if (!strcmp(name, "max_depth")) max_depth = atoi(val);
     if (!strcmp(name, "nthread")) nthread = atoi(val);
     if (!strcmp(name, "default_direction")) {
@@ -82,31 +87,31 @@ struct TrainParam{
   }
   // calculate the cost of loss function
   inline double CalcGain(double sum_grad, double sum_hess) const {
-    if (sum_hess < min_child_weight) {
-      return 0.0;
+    if (sum_hess < min_child_weight) return 0.0;
+    if (reg_alpha == 0.0f) {
+      return Sqr(sum_grad) / (sum_hess + reg_lambda);
+    } else {
+      return Sqr(ThresholdL1(sum_grad, reg_alpha)) / (sum_hess + reg_lambda); 
     }
-    switch (reg_method) {
-      case 1 : return Sqr(ThresholdL1(sum_grad, reg_lambda)) / sum_hess;
-      case 2 : return Sqr(sum_grad) / (sum_hess + reg_lambda);
-      case 3 : return
-          Sqr(ThresholdL1(sum_grad, 0.5 * reg_lambda)) /
-          (sum_hess + 0.5 * reg_lambda);
-      default: return Sqr(sum_grad) / sum_hess;
+  }
+  // calculate cost of loss function with four stati
+  inline double CalcGain(double sum_grad, double sum_hess,
+                         double test_grad, double test_hess) const {
+    double w = CalcWeight(sum_grad, sum_hess);
+    double ret = test_grad * w  + 0.5 * (test_hess + reg_lambda) * Sqr(w);
+    if (reg_alpha == 0.0f) {
+      return - 2.0 * ret;
+    } else {
+      return - 2.0 * (ret + reg_alpha * std::abs(w));
     }
   }
   // calculate weight given the statistics
   inline double CalcWeight(double sum_grad, double sum_hess) const {
-    if (sum_hess < min_child_weight) {
-      return 0.0;
+    if (sum_hess < min_child_weight) return 0.0;
+    if (reg_alpha == 0.0f) {
+      return -sum_grad / (sum_hess + reg_lambda);
     } else {
-      switch (reg_method) {
-        case 1: return - ThresholdL1(sum_grad, reg_lambda) / sum_hess;
-        case 2: return - sum_grad / (sum_hess + reg_lambda);
-        case 3: return
-            - ThresholdL1(sum_grad, 0.5 * reg_lambda) /
-            (sum_hess + 0.5 * reg_lambda);
-        default: return - sum_grad / sum_hess;
-      }
+      return -ThresholdL1(sum_grad, reg_alpha) / (sum_hess + reg_lambda);
     }
   }
   /*! \brief whether need forward small to big search: default right */
@@ -153,6 +158,9 @@ struct GradStats {
   inline void Clear(void) {
     sum_grad = sum_hess = 0.0f;
   }
+  /*! \brief check if necessary information is ready */
+  inline static void CheckInfo(const BoosterInfo &info) {
+  }
   /*!
    * \brief accumulate statistics,
    * \param gpair the vector storing the gradient statistics
@@ -188,14 +196,88 @@ struct GradStats {
   }
   /*! \brief set leaf vector value based on statistics */
   inline void SetLeafVec(const TrainParam &param, bst_float *vec) const{
-  }
- protected:
+  }  
+  // constructor to allow inheritance
+  GradStats(void) {}
   /*! \brief add statistics to the data */
   inline void Add(double grad, double hess) {
     sum_grad += grad; sum_hess += hess;
   }
 };
 
+/*! \brief vectorized cv statistics */
+template<unsigned vsize>
+struct CVGradStats : public GradStats {
+  // additional statistics
+  GradStats train[vsize], valid[vsize];
+  // constructor
+  explicit CVGradStats(const TrainParam &param) {
+    utils::Check(param.size_leaf_vector == vsize,
+                 "CVGradStats: vsize must match size_leaf_vector");
+    this->Clear();
+  }
+  /*! \brief check if necessary information is ready */
+  inline static void CheckInfo(const BoosterInfo &info) {
+    utils::Check(info.fold_index.size() != 0,
+                 "CVGradStats: require fold_index");
+  }
+  /*! \brief clear the statistics */
+  inline void Clear(void) {
+    GradStats::Clear();
+    for (unsigned i = 0; i < vsize; ++i) {
+      train[i].Clear(); valid[i].Clear();
+    }
+  }
+  inline void Add(const std::vector<bst_gpair> &gpair,
+                  const BoosterInfo &info,
+                  bst_uint ridx) {
+    GradStats::Add(gpair[ridx].grad, gpair[ridx].hess);
+    const size_t step = info.fold_index.size();
+    for (unsigned i = 0; i < vsize; ++i) {
+      const bst_gpair &b = gpair[(i + 1) * step + ridx];
+      if (info.fold_index[ridx] == i) {
+        valid[i].Add(b.grad, b.hess);
+      } else {
+        train[i].Add(b.grad, b.hess);
+      }
+    }
+  }
+  /*! \brief calculate gain of the solution */
+  inline double CalcGain(const TrainParam &param) const {
+    double ret = 0.0;
+    for (unsigned i = 0; i < vsize; ++i) {
+      ret += param.CalcGain(train[i].sum_grad,
+                            train[i].sum_hess,
+                            vsize * valid[i].sum_grad,
+                            vsize * valid[i].sum_hess);      
+    }
+    return ret / vsize;
+  }
+  /*! \brief add statistics to the data */
+  inline void Add(const CVGradStats &b) {
+    GradStats::Add(b);
+    for (unsigned i = 0; i < vsize; ++i) {
+      train[i].Add(b.train[i]);
+      valid[i].Add(b.valid[i]);
+    }
+  }
+  /*! \brief set current value to a - b */
+  inline void SetSubstract(const CVGradStats &a, const CVGradStats &b) {
+    GradStats::SetSubstract(a, b);
+    for (int i = 0; i < vsize; ++i) {
+      train[i].SetSubstract(a.train[i], b.train[i]);
+      valid[i].SetSubstract(a.valid[i], b.valid[i]);
+    }
+  }
+  /*! \brief set leaf vector value based on statistics */
+  inline void SetLeafVec(const TrainParam &param, bst_float *vec) const{
+    for (int i = 0; i < vsize; ++i) {
+      vec[i] = param.learning_rate *
+          param.CalcWeight(train[i].sum_grad, train[i].sum_hess);
+    }
+  }
+};
+
 /*! 
  * \brief statistics that is helpful to store 
  *   and represent a split solution for the tree
diff --git a/src/tree/updater.h b/src/tree/updater.h
index b33ee1833..91e9c4079 100644
--- a/src/tree/updater.h
+++ b/src/tree/updater.h
@@ -62,6 +62,8 @@ inline IUpdater<FMatrix>* CreateUpdater(const char *name) {
   if (!strcmp(name, "prune")) return new TreePruner<FMatrix>();
   if (!strcmp(name, "refresh")) return new TreeRefresher<FMatrix, GradStats>();
   if (!strcmp(name, "grow_colmaker")) return new ColMaker<FMatrix, GradStats>();
+  if (!strcmp(name, "grow_colmaker2")) return new ColMaker<FMatrix, CVGradStats<2> >();
+  if (!strcmp(name, "grow_colmaker5")) return new ColMaker<FMatrix, CVGradStats<5> >();
   utils::Error("unknown updater:%s", name);
   return NULL;
 }
diff --git a/src/tree/updater_colmaker-inl.hpp b/src/tree/updater_colmaker-inl.hpp
index 0c679e748..e26f2ada4 100644
--- a/src/tree/updater_colmaker-inl.hpp
+++ b/src/tree/updater_colmaker-inl.hpp
@@ -27,6 +27,7 @@ class ColMaker: public IUpdater<FMatrix> {
                       const FMatrix &fmat,
                       const BoosterInfo &info,
                       const std::vector<RegTree*> &trees) {
+    TStats::CheckInfo(info);
     // rescale learning rate according to size of trees
     float lr = param.learning_rate;
     param.learning_rate = lr / trees.size();
@@ -81,7 +82,6 @@ class ColMaker: public IUpdater<FMatrix> {
                         RegTree *p_tree) {
       this->InitData(gpair, fmat, info.root_index, *p_tree);
       this->InitNewNode(qexpand, gpair, fmat, info, *p_tree);
-
       for (int depth = 0; depth < param.max_depth; ++depth) {
         this->FindSplit(depth, this->qexpand, gpair, fmat, info, p_tree);
         this->ResetPosition(this->qexpand, fmat, *p_tree);