diff --git a/cpp/daal/src/externals/service_stat_ref.h b/cpp/daal/src/externals/service_stat_ref.h
index 0ff35505527..be71b5921ba 100644
--- a/cpp/daal/src/externals/service_stat_ref.h
+++ b/cpp/daal/src/externals/service_stat_ref.h
@@ -26,6 +26,7 @@
 #define __SERVICE_STAT_REF_H__
 
 #include "src/externals/service_memory.h"
+#include "src/externals/service_blas_ref.h"
 
 typedef void (*func_type)(DAAL_INT, DAAL_INT, DAAL_INT, void *);
 extern "C"
@@ -173,7 +174,57 @@ struct RefStatistics<double, cpu>
     static int xcp(double * data, __int64 nFeatures, __int64 nVectors, double * nPreviousObservations, double * sum, double * crossProduct,
                    __int64 method)
     {
-        int errcode = 0;
+        int errcode     = 0;
+        double * sumOld = NULL;
+        double accWtOld = *nPreviousObservations;
+        double accWt    = *nPreviousObservations + nVectors;
+        if (accWtOld)
+        {
+            sumOld = daal::services::internal::service_calloc<double, cpu>(nFeatures, sizeof(double));
+            for (DAAL_INT i = 0; i < nFeatures; ++i)
+            {
+                sumOld[i] = sum[i];
+            }
+        }
+        for (DAAL_INT i = 0; i < nVectors; ++i)
+        {
+            for (DAAL_INT j = 0; j < nFeatures; ++j) // if accWtOld = 0, overwrite sum
+            {
+                if (accWtOld != 0)
+                {
+                    sum[j] += data[i * nFeatures + j];
+                }
+                else
+                {
+                    if (i == 0)
+                        sum[j] = data[i * nFeatures + j]; //overwrite the current sum
+                    else
+                        sum[j] += data[i * nFeatures + j];
+                }
+            }
+        }
+        daal::internal::ref::OpenBlas<double, cpu> blasInst;
+        DAAL_INT one = 1;
+        char transa  = 'N';
+        char transb  = 'N';
+        double alpha = -1.0 / accWt;
+        double beta  = accWtOld ? 1.0 : 0.0; // if accWtOld = 0, overwrite the cross product
+        // -S S^t/accWt
+        blasInst.xgemm(&transa, &transb, &nFeatures, &nFeatures, &one, &alpha, sum, &nFeatures, sum, &one, &beta, crossProduct, &nFeatures);
+        beta = 1.0;
+        if (accWtOld)
+        {
+            alpha = 1.0 / accWtOld;
+            // S_old S_old^t/accWtOld
+            blasInst.xgemm(&transa, &transb, &nFeatures, &nFeatures, &one, &alpha, sumOld, &nFeatures, sumOld, &one, &beta, crossProduct, &nFeatures);
+        }
+        transb = 'T';
+        alpha  = 1.0;
+
+        // X X^t
+        blasInst.xgemm(&transa, &transb, &nFeatures, &nFeatures, &nVectors, &alpha, data, &nFeatures, data, &nFeatures, &beta, crossProduct,
+                       &nFeatures);
+        if (accWtOld) daal::services::daal_free(sumOld);
 
         return errcode;
     }
@@ -284,7 +335,58 @@ struct RefStatistics<float, cpu>
     static int xcp(float * data, __int64 nFeatures, __int64 nVectors, float * nPreviousObservations, float * sum, float * crossProduct,
                    __int64 method)
     {
-        int errcode = 0;
+        int errcode    = 0;
+        float * sumOld = NULL;
+        float accWtOld = *nPreviousObservations;
+        float accWt    = *nPreviousObservations + nVectors;
+        if (accWtOld)
+        {
+            sumOld = daal::services::internal::service_calloc<float, cpu>(nFeatures, sizeof(float));
+            for (DAAL_INT i = 0; i < nFeatures; ++i)
+            {
+                sumOld[i] = sum[i];
+            }
+        }
+        for (DAAL_INT i = 0; i < nVectors; ++i)
+        {
+            for (DAAL_INT j = 0; j < nFeatures; ++j) // if accWtOld = 0, overwrite sum
+            {
+                if (accWtOld != 0)
+                {
+                    sum[j] += data[i * nFeatures + j];
+                }
+                else
+                {
+                    if (i == 0)
+                        sum[j] = data[i * nFeatures + j]; //overwrite the current sum
+                    else
+                        sum[j] += data[i * nFeatures + j];
+                }
+            }
+        }
+        daal::internal::ref::OpenBlas<float, cpu> blasInst;
+        DAAL_INT one = 1;
+        char transa  = 'N';
+        char transb  = 'N';
+        float alpha  = -1.0 / accWt;
+        float beta   = accWtOld ? 1.0 : 0.0; // if accWtOld = 0, overwrite the cross product
+        // -S S^t/accWt
+        blasInst.xgemm(&transa, &transb, &nFeatures, &nFeatures, &one, &alpha, sum, &nFeatures, sum, &one, &beta, crossProduct, &nFeatures);
+        beta = 1.0;
+        if (accWtOld)
+        {
+            alpha = 1.0 / accWtOld;
+            // S_old S_old^t/accWtOld
+            blasInst.xgemm(&transa, &transb, &nFeatures, &nFeatures, &one, &alpha, sumOld, &nFeatures, sumOld, &one, &beta, crossProduct, &nFeatures);
+        }
+        transb = 'T';
+        alpha  = 1.0;
+
+        // X X^t
+        blasInst.xgemm(&transa, &transb, &nFeatures, &nFeatures, &nVectors, &alpha, data, &nFeatures, data, &nFeatures, &beta, crossProduct,
+                       &nFeatures);
+
+        if (accWtOld) daal::services::daal_free(sumOld);
 
         return errcode;
     }