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diff --git a/src/main/java/org/apache/commons/math3/fitting/WeightedObservedPoints.java b/src/main/java/org/apache/commons/math3/fitting/WeightedObservedPoints.java
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+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.commons.math3.fitting;
+
+import java.io.Serializable;
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Simple container for weighted observed points used in {@link AbstractCurveFitter curve fitting}
+ * algorithms.
+ *
+ * @since 3.3
+ */
+public class WeightedObservedPoints implements Serializable {
+    /** Serializable version id. */
+    private static final long serialVersionUID = 20130813L;
+
+    /** Observed points. */
+    private final List<WeightedObservedPoint> observations = new ArrayList<WeightedObservedPoint>();
+
+    /**
+     * Adds a point to the sample. Calling this method is equivalent to calling {@code add(1.0, x,
+     * y)}.
+     *
+     * @param x Abscissa of the point.
+     * @param y Observed value at {@code x}. After fitting we should have {@code f(x)} as close as
+     *     possible to this value.
+     * @see #add(double, double, double)
+     * @see #add(WeightedObservedPoint)
+     * @see #toList()
+     */
+    public void add(double x, double y) {
+        add(1d, x, y);
+    }
+
+    /**
+     * Adds a point to the sample.
+     *
+     * @param weight Weight of the observed point.
+     * @param x Abscissa of the point.
+     * @param y Observed value at {@code x}. After fitting we should have {@code f(x)} as close as
+     *     possible to this value.
+     * @see #add(double, double)
+     * @see #add(WeightedObservedPoint)
+     * @see #toList()
+     */
+    public void add(double weight, double x, double y) {
+        observations.add(new WeightedObservedPoint(weight, x, y));
+    }
+
+    /**
+     * Adds a point to the sample.
+     *
+     * @param observed Observed point to add.
+     * @see #add(double, double)
+     * @see #add(double, double, double)
+     * @see #toList()
+     */
+    public void add(WeightedObservedPoint observed) {
+        observations.add(observed);
+    }
+
+    /**
+     * Gets a <em>snapshot</em> of the observed points. The list of stored points is copied in order
+     * to ensure that modification of the returned instance does not affect this container.
+     * Conversely, further modification of this container (through the {@code add} or {@code clear}
+     * methods) will not affect the returned list.
+     *
+     * @return the observed points, in the order they were added to this container.
+     * @see #add(double, double)
+     * @see #add(double, double, double)
+     * @see #add(WeightedObservedPoint)
+     */
+    public List<WeightedObservedPoint> toList() {
+        // The copy is necessary to ensure thread-safety because of the
+        // "clear" method (which otherwise would be able to empty the
+        // list of points while it is being used by another thread).
+        return new ArrayList<WeightedObservedPoint>(observations);
+    }
+
+    /** Removes all observations from this container. */
+    public void clear() {
+        observations.clear();
+    }
+}