diff --git a/core/src/main/java/org/elasticsearch/search/aggregations/metrics/stats/extended/ExtendedStatsAggregator.java b/core/src/main/java/org/elasticsearch/search/aggregations/metrics/stats/extended/ExtendedStatsAggregator.java
index 104cd36367b..c9413e15d2a 100644
--- a/core/src/main/java/org/elasticsearch/search/aggregations/metrics/stats/extended/ExtendedStatsAggregator.java
+++ b/core/src/main/java/org/elasticsearch/search/aggregations/metrics/stats/extended/ExtendedStatsAggregator.java
@@ -193,7 +193,7 @@ public class ExtendedStatsAggregator extends NumericMetricsAggregator.MultiValue
 
     @Override
     public InternalAggregation buildEmptyAggregation() {
-        return new InternalExtendedStats(name, 0, 0d, Double.POSITIVE_INFINITY, Double.NEGATIVE_INFINITY, 0d, 0d, formatter, pipelineAggregators(),
+        return new InternalExtendedStats(name, 0, 0d, Double.POSITIVE_INFINITY, Double.NEGATIVE_INFINITY, 0d, sigma, formatter, pipelineAggregators(),
                 metaData());
     }
 
diff --git a/core/src/main/java/org/elasticsearch/search/aggregations/metrics/stats/extended/InternalExtendedStats.java b/core/src/main/java/org/elasticsearch/search/aggregations/metrics/stats/extended/InternalExtendedStats.java
index 9fac5809cef..fe83e045952 100644
--- a/core/src/main/java/org/elasticsearch/search/aggregations/metrics/stats/extended/InternalExtendedStats.java
+++ b/core/src/main/java/org/elasticsearch/search/aggregations/metrics/stats/extended/InternalExtendedStats.java
@@ -148,6 +148,9 @@ public class InternalExtendedStats extends InternalStats implements ExtendedStat
         double sumOfSqrs = 0;
         for (InternalAggregation aggregation : aggregations) {
             InternalExtendedStats stats = (InternalExtendedStats) aggregation;
+            if (stats.sigma != sigma) {
+                throw new IllegalStateException("Cannot reduce other stats aggregations that have a different sigma");
+            }
             sumOfSqrs += stats.getSumOfSquares();
         }
         final InternalStats stats = super.doReduce(aggregations, reduceContext);
diff --git a/modules/lang-groovy/src/test/java/org/elasticsearch/messy/tests/ExtendedStatsTests.java b/modules/lang-groovy/src/test/java/org/elasticsearch/messy/tests/ExtendedStatsTests.java
index c38e8f2a979..d7fc77c9ccb 100644
--- a/modules/lang-groovy/src/test/java/org/elasticsearch/messy/tests/ExtendedStatsTests.java
+++ b/modules/lang-groovy/src/test/java/org/elasticsearch/messy/tests/ExtendedStatsTests.java
@@ -19,7 +19,6 @@
 package org.elasticsearch.messy.tests;
 
 import org.elasticsearch.action.search.SearchResponse;
-import org.elasticsearch.action.search.ShardSearchFailure;
 import org.elasticsearch.plugins.Plugin;
 import org.elasticsearch.script.Script;
 import org.elasticsearch.script.ScriptService.ScriptType;
@@ -129,6 +128,24 @@ public class ExtendedStatsTests extends AbstractNumericTestCase {
         assertThat(Double.isNaN(stats.getStdDeviationBound(ExtendedStats.Bounds.LOWER)), is(true));
     }
 
+    public void testPartiallyUnmapped() {
+        double sigma = randomDouble() * 5;
+        ExtendedStats s1 = client().prepareSearch("idx")
+                .addAggregation(extendedStats("stats").field("value").sigma(sigma)).get()
+                .getAggregations().get("stats");
+        ExtendedStats s2 = client().prepareSearch("idx", "idx_unmapped")
+                .addAggregation(extendedStats("stats").field("value").sigma(sigma)).get()
+                .getAggregations().get("stats");
+        assertEquals(s1.getAvg(), s2.getAvg(), 1e-10);
+        assertEquals(s1.getCount(), s2.getCount());
+        assertEquals(s1.getMin(), s2.getMin(), 0d);
+        assertEquals(s1.getMax(), s2.getMax(), 0d);
+        assertEquals(s1.getStdDeviation(), s2.getStdDeviation(), 1e-10);
+        assertEquals(s1.getSumOfSquares(), s2.getSumOfSquares(), 1e-10);
+        assertEquals(s1.getStdDeviationBound(Bounds.LOWER), s2.getStdDeviationBound(Bounds.LOWER), 1e-10);
+        assertEquals(s1.getStdDeviationBound(Bounds.UPPER), s2.getStdDeviationBound(Bounds.UPPER), 1e-10);
+    }
+
     @Override
     public void testSingleValuedField() throws Exception {
         double sigma = randomDouble() * randomIntBetween(1, 10);
@@ -584,17 +601,6 @@ public class ExtendedStatsTests extends AbstractNumericTestCase {
         }
     }
 
-    private void assertShardExecutionState(SearchResponse response, int expectedFailures) throws Exception {
-        ShardSearchFailure[] failures = response.getShardFailures();
-        if (failures.length != expectedFailures) {
-            for (ShardSearchFailure failure : failures) {
-                logger.error("Shard Failure: {}", failure.getCause(), failure);
-            }
-            fail("Unexpected shard failures!");
-        }
-        assertThat("Not all shards are initialized", response.getSuccessfulShards(), equalTo(response.getTotalShards()));
-    }
-
     private void checkUpperLowerBounds(ExtendedStats stats, double sigma) {
         assertThat(stats.getStdDeviationBound(ExtendedStats.Bounds.UPPER), equalTo(stats.getAvg() + (stats.getStdDeviation() * sigma)));
         assertThat(stats.getStdDeviationBound(ExtendedStats.Bounds.LOWER), equalTo(stats.getAvg() - (stats.getStdDeviation() * sigma)));
diff --git a/modules/lang-groovy/src/test/java/org/elasticsearch/messy/tests/StatsTests.java b/modules/lang-groovy/src/test/java/org/elasticsearch/messy/tests/StatsTests.java
index 9af5e086a34..beb462fea00 100644
--- a/modules/lang-groovy/src/test/java/org/elasticsearch/messy/tests/StatsTests.java
+++ b/modules/lang-groovy/src/test/java/org/elasticsearch/messy/tests/StatsTests.java
@@ -31,6 +31,8 @@ import org.elasticsearch.search.aggregations.bucket.terms.Terms;
 import org.elasticsearch.search.aggregations.bucket.terms.Terms.Order;
 import org.elasticsearch.search.aggregations.metrics.AbstractNumericTestCase;
 import org.elasticsearch.search.aggregations.metrics.stats.Stats;
+import org.elasticsearch.search.aggregations.metrics.stats.extended.ExtendedStats;
+import org.elasticsearch.search.aggregations.metrics.stats.extended.ExtendedStats.Bounds;
 
 import java.util.Collection;
 import java.util.Collections;
@@ -40,6 +42,7 @@ import java.util.Map;
 
 import static org.elasticsearch.index.query.QueryBuilders.matchAllQuery;
 import static org.elasticsearch.index.query.QueryBuilders.termQuery;
+import static org.elasticsearch.search.aggregations.AggregationBuilders.extendedStats;
 import static org.elasticsearch.search.aggregations.AggregationBuilders.filter;
 import static org.elasticsearch.search.aggregations.AggregationBuilders.global;
 import static org.elasticsearch.search.aggregations.AggregationBuilders.histogram;
@@ -106,6 +109,19 @@ public class StatsTests extends AbstractNumericTestCase {
         assertThat(stats.getCount(), equalTo(0L));
     }
 
+    public void testPartiallyUnmapped() {
+        Stats s1 = client().prepareSearch("idx")
+                .addAggregation(stats("stats").field("value")).get()
+                .getAggregations().get("stats");
+        ExtendedStats s2 = client().prepareSearch("idx", "idx_unmapped")
+                .addAggregation(stats("stats").field("value")).get()
+                .getAggregations().get("stats");
+        assertEquals(s1.getAvg(), s2.getAvg(), 1e-10);
+        assertEquals(s1.getCount(), s2.getCount());
+        assertEquals(s1.getMin(), s2.getMin(), 0d);
+        assertEquals(s1.getMax(), s2.getMax(), 0d);
+    }
+
     @Override
     public void testSingleValuedField() throws Exception {
         SearchResponse searchResponse = client().prepareSearch("idx")