fix error in marginal effects example
diff --git a/src/ports/postgres/modules/regress/marginal.sql_in b/src/ports/postgres/modules/regress/marginal.sql_in
index a19424e..3cb3f8a 100644
--- a/src/ports/postgres/modules/regress/marginal.sql_in
+++ b/src/ports/postgres/modules/regress/marginal.sql_in
@@ -38,9 +38,7 @@
 source table.
 
 MADlib provides marginal effects regression functions for linear, logistic and
-multinomial logistic regressions.
-
-@warning The margins_logregr() and margins_mlogregr() functions have been deprecated in favor of the margins() function.
+multinomial logistic regressions. The implementation is similar to reference [1].
 
 @anchor margins
 @par Marginal Effects with Interaction Terms
@@ -321,11 +319,11 @@
 SELECT madlib.logregr_train( 'patients',
                              'model_table',
                              'second_attack',
-                             'ARRAY[1, treatment, trait_anxiety, treatment^2, treatment * trait_anxiety]'
+                             'ARRAY[1, treatment, trait_anxiety, treatment * trait_anxiety]'
                            );
 SELECT madlib.margins( 'model_table',
                        'margins_table',
-                       'intercept, treatment, trait_anxiety, treatment^2, treatment*trait_anxiety',
+                       'intercept, treatment, trait_anxiety, treatment*trait_anxiety',
                        NULL,
                        NULL
                      );
@@ -347,7 +345,7 @@
 DROP TABLE IF EXISTS result_table;
 SELECT madlib.margins( 'model_table',
                        'result_table',
-                       'i, tre, tra, tre^2, tre*tra',
+                       'i, tre, tra, tre*tra',
                        NULL,
                        'tre'
                      );
@@ -475,7 +473,7 @@
 @literature
 
 
-[1] mfx function in STATA: http://www.stata.com/help.cgi?mfx_option
+[1] Marginal effects in Stata: https://www.stata.com/
 
 @anchor related
 @par Related Topics