diff --git a/hoot-rnd/src/main/cpp/hoot/rnd/conflate/matching/ScoreMatchesDiff.h b/hoot-rnd/src/main/cpp/hoot/rnd/conflate/matching/ScoreMatchesDiff.h
new file mode 100644
index 0000000..db8c550
--- /dev/null
+++ b/hoot-rnd/src/main/cpp/hoot/rnd/conflate/matching/ScoreMatchesDiff.h
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+/*
+ * This file is part of Hootenanny.
+ *
+ * Hootenanny is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ * --------------------------------------------------------------------
+ *
+ * The following copyright notices are generated automatically. If you
+ * have a new notice to add, please use the format:
+ * " * @copyright Copyright ..."
+ * This will properly maintain the copyright information. DigitalGlobe
+ * copyrights will be updated automatically.
+ *
+ * @copyright Copyright (C) 2019 DigitalGlobe (http://www.digitalglobe.com/)
+ */
+#ifndef SCORE_MATCHES_DIFF_H
+#define SCORE_MATCHES_DIFF_H
+
+// Hoot
+#include <hoot/core/elements/OsmMap.h>
+#include <hoot/core/conflate/matching/MatchType.h>
+
+// Qt
+#include <QMap>
+#include <QFile>
+#include <QTextStream>
+#include <QSet>
+
+namespace hoot
+{
+
+/**
+ * Compares two output files from score-matches and writes a file with the differences in the match
+ * scoring. Useful when trying to determine why conflation logic changes results in increased
+ * incorrect matches.
+ */
+class ScoreMatchesDiff
+{
+public:
+
+ ScoreMatchesDiff();
+ ~ScoreMatchesDiff();
+
+ /**
+ * Calculates the differential between to separate score-matches outputs
+ *
+ * @param input1 the first file to examine
+ * @param input2 the second file to examine
+ */
+ void calculateDiff(const QString& input1, const QString& input2);
+
+ /**
+ * Prints previously calculated match scoring differential
+ *
+ * @param output the file to write the differential information to
+ * @return true if the printing was successful; false otherwise
+ */
+ bool printDiff(const QString& output);
+
+ /**
+ * Clears calculated differential data
+ */
+ void clear();
+
+private:
+
+ friend class ScoreMatchesDiffTest;
+
+ // IDs of elements involved in a wrong match from the second input that aren't involved in a wrong
+ // match in the first input.
+ QSet<ElementId> _newlyWrong;
+ // IDs of elements involved in a correct match from the second input that aren't involved in a
+ // correct match in the first input.
+ QSet<ElementId> _newlyCorrect;
+ // difference in match status between any element that wasn't involved in a wrong match in the
+ // first input but is involved in a wrong match in the second
+ QMap<QString, QSet<ElementId>> _newlyWrongMatchSwitches;
+ // difference in match status between any element that was involved in a wrong match in the
+ // first input but isn't involved in a wrong match in the second
+ QMap<QString, QSet<ElementId>> _newlyCorrectMatchSwitches;
+
+ // elements added to the second file when compared to the first
+ QSet<ElementId> _elementIdsAdded;
+ // elements removed from the first file when compared to the second
+ QSet<ElementId> _elementIdsRemoved;
+
+ // number of manual matches made
+ int _numManualMatches;
+
+ // difference in number of reviews in the two inputs
+ int _reviewDifferential;
+
+ QString _input1;
+ QString _input2;
+ QString _output;
+ std::shared_ptr<QFile> _outputFile;
+
+ std::shared_ptr<QFile> _getOutputFile(const QString& outputPath);
+
+ /*
+ * Returns all element IDs in the map
+ */
+ QSet<ElementId> _getAllIds(const ConstOsmMapPtr& map);
+
+ /*
+ * Returns all elements with the given match status (hoot:expected or hoot:actual), grouped by ID
+ */
+ QMap<ElementId, QString> _getMatchStatuses(const ConstOsmMapPtr& map, const QString& tagKey);
+
+ /*
+ * Returns the IDS of all elements involved in a wrong match
+ */
+ QSet<ElementId> _getWrong(const ConstOsmMapPtr& map);
+
+ /*
+ * For a given set of elements, groups them by how their match statuses changed between the two
+ * inputs
+ */
+ QMap<QString, QSet<ElementId>> _getMatchScoringDiff(
+ const QSet<ElementId>& elementIds, const QMap<ElementId, QString>& actualTagMappings1,
+ const QMap<ElementId, QString>& actualTagMappings2);
+
+ /*
+ * Records element differences between the two inputs
+ */
+ void _setAddedAndRemovedElements(
+ const QSet<ElementId>& all1Ids, const QSet<ElementId>& all2Ids,
+ QSet<ElementId>& elementIdsAdded, QSet<ElementId>& elementIdsRemoved);
+
+ void _writeConflateStatusSummary(QTextStream& out);
+ void _writeConflateStatusDetail(QTextStream& out);
+};
+
+}
+
+#endif // SCORE_MATCHES_DIFF_H