First working version of the "data quality stats" feature.

9 files changed, 480 insertions, 42 deletions

diff --git a/src/bm/bm.pro b/src/bm/bm.pro
index cff490b..70ae5dd 100644
--- a/src/bm/bm.pro
+++ b/src/bm/bm.pro
@@ -1,8 +1,10 @@
 TEMPLATE = lib
 CONFIG += shared
 TARGET = bm
-SOURCES += bm.cpp bmrequest.cpp bmmisc.cpp plotter.cpp resulthistoryinfo.cpp cache.cpp index.cpp
-HEADERS += bm.h bmrequest.h bmmisc.h plotter.h resulthistoryinfo.h cache.h index.h
+SOURCES += bm.cpp bmrequest.cpp bmmisc.cpp plotter.cpp resulthistoryinfo.cpp cache.cpp index.cpp \
+           dataqualitystats.cpp
+HEADERS += bm.h bmrequest.h bmmisc.h plotter.h resulthistoryinfo.h cache.h index.h \
+           dataqualitystats.h
 QT += network
 QT += xml
 QT += sql
diff --git a/src/bm/bmrequest.cpp b/src/bm/bmrequest.cpp
index 50c05a4..765e808 100644
--- a/src/bm/bmrequest.cpp
+++ b/src/bm/bmrequest.cpp
@@ -23,6 +23,7 @@
 
 #include "bmrequest.h"
 #include "resulthistoryinfo.h"
+#include "dataqualitystats.h"
 #include "plotter.h"
 #include "cache.h"
 #include <QSqlDatabase>
@@ -5100,11 +5101,14 @@ QByteArray BMRequest_IndexGetValues::toReplyBuffer()
 
         QList<qreal> indexValues;
         QList<int> contrCounts;
+        QString error_;
         QList<QList<Index::RankedInfo> > topContr; // Top contributors for each index value
         const int topContrLimit = 10; // ### hard-coded for now!
-        QString error_;
+        DataQualityStats dqStats(dqStatsDiffTol, dqStatsStabTol); // Stats for all contributors
+
         if (!index.computeValues(
-                &indexValues, &baseValuePos, &contrCounts, &error_, &topContr, topContrLimit)) {
+                &indexValues, &baseValuePos, &contrCounts, &error_, &topContr, topContrLimit,
+                dataQualityStats ? &dqStats : static_cast<DataQualityStats *>(0))) {
             return xmlConvert(
                 errorReply(name(), QString("failed to compute index (2): %1").arg(error_)));
         }
@@ -5133,6 +5137,35 @@ QByteArray BMRequest_IndexGetValues::toReplyBuffer()
 
             reply += "</value>";
         }
+
+        if (dataQualityStats) {
+            // Add data quality stats to reply ...
+
+            reply += QString("<dataQualityStats diffTol=\"%1\" stabTol=\"%2\">")
+                .arg(dqStatsDiffTol).arg(dqStatsStabTol);
+
+            const QMap<int, int> totalMaxESSFreq_ = dqStats.totalMaxESSFreq();
+            {
+                QMap<int, int>::const_iterator it;
+                for (it = totalMaxESSFreq_.constBegin(); it != totalMaxESSFreq_.constEnd(); ++it)
+                    reply += QString("<totMaxESSCountFreq count=\"%1\" freq=\"%2\" />")
+                        .arg(it.key()).arg(it.value());
+            }
+
+            const QMap<int, QPair<qreal, qreal> > stabFracPercentiles_ =
+                dqStats.stabFracPercentiles();
+            {
+                QMap<int, QPair<qreal, qreal> >::const_iterator it;
+                for (it = stabFracPercentiles_.constBegin();
+                     it != stabFracPercentiles_.constEnd(); ++it)
+                    reply += QString("<stabFracPercentile p=\"%1\" val=\"%2\" val2=\"%3\" />")
+                        .arg(it.key())
+                        .arg(it.value().first)
+                        .arg(it.value().second);
+            }
+
+            reply += "</dataQualityStats>";
+        }
     }
 
 
@@ -5392,7 +5425,15 @@ void BMRequest_IndexGetValues::handleReply_HTML(const QStringList &args) const
 
 
     // *** Meta information (characterizing the results) ***
-    reply += "\n<br /><br /><table>\n";
+
+    reply += "\n<br /><br /><table style=\"border:0px\">\n";
+    reply += "<tr>\n";
+
+    // Left main table ...
+
+    reply += "<td style=\"border:0px\">\n";
+
+    reply += "<table>\n";
     int baseTimestamp = argsElem.attributeNode("baseTimestamp").value().toInt(&ok);
     Q_ASSERT(ok);
     if (baseTimestamp < 0)
@@ -5427,7 +5468,7 @@ void BMRequest_IndexGetValues::handleReply_HTML(const QStringList &args) const
 
 
     // 'Filters' table ...
-    reply += "\n<br /><br />Filters:<table>\n";
+    reply += "\n<br /><br /><b>Filters:</b><table>\n";
     appendToFilterTable(testCaseFilter, "Test case", &reply);
     appendToFilterTable(metricFilter, "Metric", &reply);
     appendToFilterTable(platformFilter, "Platform", &reply);
@@ -5436,7 +5477,7 @@ void BMRequest_IndexGetValues::handleReply_HTML(const QStringList &args) const
     reply += "</table>";
 
     // 'Number of contributors' table ...
-    reply += "\n<br /><br />Number of contributors:<table style=\"text-align:right\">\n";
+    reply += "\n<br /><br /><b>Number of contributors:</b><table style=\"text-align:right\">\n";
     const int totalRH = argsElem.attributeNode("totalRH").value().toInt(&ok);
     Q_ASSERT(ok);
     reply += QString(
@@ -5468,7 +5509,8 @@ void BMRequest_IndexGetValues::handleReply_HTML(const QStringList &args) const
         }
     }
     const qreal secsInDay = 86400.0;
-    reply += "\n<br /><br />Timestamp neighbor distances:<table style=\"text-align:right\">\n";
+    reply +=
+        "\n<br /><br /><b>Timestamp neighbor distances:</b><table style=\"text-align:right\">\n";
     reply += QString("<tr><td>Min days:</td><td>%1</td></tr>\n")
         .arg((timestamps.size() < 2) ? "n/a" : QString().setNum(minDistSecs / secsInDay, 'f', 2));
     reply += QString("<tr><td>Avg days:</td><td>%1</td></tr>\n")
@@ -5478,6 +5520,127 @@ void BMRequest_IndexGetValues::handleReply_HTML(const QStringList &args) const
         .arg((timestamps.size() < 2) ? "n/a" : QString().setNum(maxDistSecs / secsInDay, 'f', 2));
     reply += "</table>\n";
 
+    reply += "</td>\n";
+
+
+    // Right main table ...
+
+    reply += "<td style=\"border:0px\">\n";
+
+    QDomNodeList dqStatsNodes = doc.elementsByTagName("dataQualityStats");
+    if (dqStatsNodes.size() > 0) {
+
+        QDomElement dqStatsElem = dqStatsNodes.at(0).toElement();
+
+        // Get tolerance values ...
+        dqStatsDiffTol = dqStatsElem.attributeNode("diffTol").value().toDouble(&ok);
+        Q_ASSERT(ok);
+        dqStatsStabTol = dqStatsElem.attributeNode("stabTol").value().toInt(&ok);
+        Q_ASSERT(ok);
+
+        reply += "<fieldset><legend style=\"font-size:12\">Data Quality Statistics</legend>";
+
+        // --- BEGIN Legend table ---
+        reply += "<table style=\"border:0px\">"
+            "<tr><td style=\"border:0px; background-color:#eeeeee\">"
+            "<table style=\"border:0px\">";
+        reply += QString(
+            "<tr><td style=\"padding:1px; border:0px; text-align:right\">"
+            "Subsequence:&nbsp;</td><td style=\"padding:1px; border:0px; text-align:left\">"
+            "In the result history of any given contributor, a maximum contiguous sequence "
+            "in which all values differ by at most <u>%1 %</u>.</td></tr>")
+            .arg(dqStatsDiffTol);
+        reply += "<tr><td style=\"padding:1px; border:0px; text-align:right; font-weight:bold\">"
+            "SSC:&nbsp;</td><td style=\"padding:1px; border:0px; text-align:left\">"
+            "Subsequence count in a single contributor.</td></tr>";
+        reply += "<tr><td style=\"padding:1px; border:0px; text-align:right; font-weight:bold\">"
+            "Freq:&nbsp;</td><td style=\"padding:1px; border:0px; text-align:left\">"
+            "Frequency (number of occurrences).</td></tr>";
+        reply += QString(
+            "<tr><td style=\"padding:1px; border:0px; text-align:right\">"
+            "Stability&nbsp;fraction:&nbsp;</td><td style=\"padding:1px; border:0px; "
+            "text-align:left\">"
+            "In any given contributor, the percentage of subsequences that have a length "
+            "of at least <u>%1</u>.</td></tr>")
+            .arg(dqStatsStabTol);
+        reply += "<tr><td style=\"padding:1px; border:0px; text-align:right; font-weight:bold\">"
+            "SF:&nbsp;</td><td style=\"padding:1px; border:0px; text-align:left\">"
+            "Stability fraction in a single contributor (regardless of its subsequence count)."
+            "</td></tr>";
+        reply += "<tr><td style=\"padding:1px; border:0px; text-align:right; font-weight:bold\">"
+            "SF2:&nbsp;</td><td style=\"padding:1px; border:0px; text-align:left\">"
+            "Stability fraction in a single contributor having subsequence count >= 2."
+            "</td></tr>";
+        reply += "<tr><td style=\"padding:1px; border:0px; text-align:right; font-weight:bold\">"
+            "P<sub><i>k</i></sub>:&nbsp;</td><td style=\"padding:1px; border:0px; "
+            "text-align:left\">"
+            "The <i>k</i>th percentile of the stability fractions (i.e. the <i>maximum</i> "
+            "stability fraction of the <i>worst</i> <i>k</i>&nbsp;% of the contributors)."
+            "</td></tr>";
+        reply += "</table></td></tr></table>";
+        // --- END Legend table ---
+
+        reply += "<table style=\"border:0px\">";
+
+        // --- BEGIN Stats tables ---
+        reply += "<tr>";
+
+        // .. subsequence count ...
+        reply += "<td style=\"border:0px\"><table><tr><th>SSC</th><th>Freq</th></tr>\n";
+        QDomNodeList ssFreqNodes = dqStatsElem.elementsByTagName("totMaxESSCountFreq");
+        for (int i = 0; i < ssFreqNodes.size(); ++i) {
+            QDomElement ssFreqElem = ssFreqNodes.at(i).toElement();
+            reply += QString("<tr style=\"text-align:right\"><td>%1</td><td>%2</td></tr>\n")
+                .arg(ssFreqElem.attributeNode("count").value())
+                .arg(ssFreqElem.attributeNode("freq").value());
+        }
+        reply += "</table></td>\n";
+
+        QDomNodeList sfPercNodes = dqStatsElem.elementsByTagName("stabFracPercentile");
+
+        // .. stable fraction percentiles (all subsequence counts) ...
+        reply += "<td style=\"border:0px\"><table>"
+            "<tr><th></th><th>SF</th></tr>\n";
+        for (int i = sfPercNodes.size() - 1; i >= 0; --i) {
+            QDomElement sfPercElem = sfPercNodes.at(i).toElement();
+            reply += QString(
+                "<tr><td><b>P<sub>%1</sub></b></td><td style=\"text-align:right\">%2%</td></tr>\n")
+                .arg(sfPercElem.attributeNode("p").value())
+                .arg(QString()
+                     .setNum(sfPercElem.attributeNode("val").value().toDouble(&ok), 'f', 1));
+            Q_ASSERT(ok);
+        }
+        reply += "</table></td>\n";
+
+        // .. stable fraction percentiles (subsequence counts >= 2) ...
+        reply += "<td style=\"border:0px\"><table>"
+            "<tr><th></th><th>SF2</th></tr>\n";
+        for (int i = sfPercNodes.size() - 1; i >= 0; --i) {
+            QDomElement sfPercElem = sfPercNodes.at(i).toElement();
+            reply += QString(
+                "<tr><td><b>P<sub>%1</sub></b></td><td style=\"text-align:right\">%2%</td></tr>\n")
+                .arg(sfPercElem.attributeNode("p").value())
+                .arg(QString()
+                     .setNum(sfPercElem.attributeNode("val2").value().toDouble(&ok), 'f', 1));
+            Q_ASSERT(ok);
+        }
+        reply += "</table></td>\n";
+
+        reply += "</tr>\n";
+        // --- END Stats tables ---
+
+        reply += "</table>\n";
+
+        reply += "</fieldset>";
+    }
+
+    reply += "</td>\n";
+
+
+    reply += "</tr>\n";
+    reply += "<table>\n";
+
+
     // *** Values ***
     reply += "\n<br /><br /><table style=\"border: 0px\">\n";
     reply += "<tr style=\"border: 0px\">\n";
diff --git a/src/bm/dataqualitystats.cpp b/src/bm/dataqualitystats.cpp
new file mode 100644
index 0000000..ad6743a
--- /dev/null
+++ b/src/bm/dataqualitystats.cpp
@@ -0,0 +1,174 @@
+/****************************************************************************
+**
+** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
+** Contact: Qt Software Information (qt-info@nokia.com)
+**
+** This file is part of the BM project on Qt Labs.
+**
+** This file may be used under the terms of the GNU General Public
+** License version 2.0 or 3.0 as published by the Free Software Foundation
+** and appearing in the file LICENSE.GPL included in the packaging of
+** this file.  Please review the following information to ensure GNU
+** General Public Licensing requirements will be met:
+** http://www.fsf.org/licensing/licenses/info/GPLv2.html and
+** http://www.gnu.org/copyleft/gpl.html.
+**
+** If you are unsure which license is appropriate for your use, please
+** contact the sales department at qt-sales@nokia.com.
+**
+** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
+** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
+**
+****************************************************************************/
+
+#include "dataqualitystats.h"
+#include <QList>
+#include <QMap>
+#include <QDebug>
+
+/* NOTES
+
+Params:
+
+- diffTolerance (in percent: 0 <= x <= 100)
+- stabTolerance (a positive integer: x >= 2)
+
+-------------------------------------------------
+
+Def: An equality subsequence (ESS) is a subsequence v1, v2, ..., vn of a result history
+     for which the following condition holds:
+
+         ∀ i >= 1 : 100 * (max(vi, v1) / min(vi, v1) - 1) <= diffTolerance
+
+
+Def: A maximal equality subsequence (MaxESS) is one of the subsequences formed by
+     partitioning a result history into the smallest possible number of ESS'es.
+
+
+Def: The stability fraction (SF) of a result history is the fraction (given as a
+     percentage: 0 <= SF <= 100) of its MaxESS'es that are stable.
+     More precisely,
+
+         SF = 100 * (stableMaxESS / totalMaxESS),
+
+     where stableMaxESS is the the number of MaxESS'es that have a length of at least
+     stabTolerance and totalMaxESS is the total number of MaxESS'es.
+
+-------
+
+Stats 1: Percentile distribution of the SF values for the contributing result histories.
+
+P_95 = x -> x is the smallest SF value that is larger than or equal to that
+            of 95% of the result histories (i.e. 95% of the result histories have an SF value
+            that is smaller than or equal to x)
+
+Example:
+
+100 100 100 100 100 (good)
+100  80  30  20  10 (bad)
+
+The following 10 values: 95, 90, 80, 50, 40, 40, 40, 40, 5, 0
+gives the following percentile distribution:
+
+P_100 =  95   (the worst 100 % of the RHs have a SF of 95 or worse, and 95 is also the max SF)
+P_90  =  90   (           90                           90         )
+P_80  =  80   (           80                           80         )
+P_70  =  50   (           70                           50         )
+P_60  =  40   (           60                           40         )
+P_50  =  40   (           50                           40         )
+P_40  =  40   (           40                           40         )
+P_30  =  40   (           30                           40         )
+P_20  =   5   (           20                            5         )
+P_10  =   0   (           10                            0         )
+
+Note: The quality of a RH is proportional to its SF value, so we want the percentile distribution
+      to start (at P_100) as high as possible (ideally at 100), and end (at P_10) as high
+      as possible.
+
+*/
+
+
+// ### 2 B DOCUMENTED!
+void DataQualityStats::compute(const QList<ResultHistoryInfo *> &rhInfos)
+{
+    // Step 1: Compute the MaxESSTotalCount and MaxESSStableCount for each RH
+    //         (compute for the exact median-smoothed values that formed the
+    //         basis for computing the index, i.e. simply ignore the outliers)
+    //
+    // Step 2: Compute the complete distribution of MaxESSTotalCount
+    //         (note that the number of distinct counts are likely to be only a small
+    //         fraction of the number of RHs):
+    //
+    //           TC(c1) = <# of RHs with a MaxESSTotalCount of c1>
+    //           TC(c2) = <# of RHs with a MaxESSTotalCount of c2>
+    //           ...
+    //           TC(cN) = <# of RHs with a MaxESSTotalCount of cN>
+    //
+    //         (TC = Total Count, and N is number of distinct counts)
+    //          
+    // Step 3: Compute the percentile distribution (for the 10 levels 10%, 20%, ..., 100%)
+    //         of the SF (stability fraction) values (where the SF for a given
+    //         RH is MaxESSStableCount / MaxESSTotalCount):
+    //
+    //           SFP(100) = <the max SF value for the worst 100% of the RHs (i.e. all RHs!)>
+    //           SFP(90)  = <the max SF value for the worst  90% of the RHs>
+    //           SFP(80)  = <the max SF value for the worst  80% of the RHs>
+    //           ...
+    //           SFP(10)  = <the max SF value for the worst  10% of the RHs>
+    //
+    //           (SFP = Stability Fraction Percentile)
+
+
+
+    // *** Step 1: Extract total and stable MaxESS counts for each result history ***
+
+    Q_ASSERT(diffTolerance >= 0.0);
+    Q_ASSERT(stabTolerance >= 2);
+
+    QList<int> totalMaxESS;
+    QList<int> stableMaxESS;
+
+    for (int i = 0; i < rhInfos.size(); ++i) {
+        int total = 0;
+        int stable = 0;
+        rhInfos.at(i)->computeMaxESSStats(diffTolerance, stabTolerance, &total, &stable);
+        totalMaxESS.append(total);
+        stableMaxESS.append(stable);
+    }
+
+
+    // *** Step 2: Compute the frequency distribution of the total MaxESS counts ***
+    totalMaxESSFreq_.clear();
+    for (int i = 0; i < totalMaxESS.size(); ++i)
+        ++(totalMaxESSFreq_[totalMaxESS.at(i)]);
+
+
+    // *** Step 3: Compute the percentile distribution of the stability fractions ***
+
+    // All subsequence counts (subsequence counts >= 0):
+    QList<qreal> stabFractions0;
+
+    // Subsequence counts >= 2 (i.e. result histories with actual changes in them and thus
+    //                          the ones that are really interesting):
+    QList<qreal> stabFractions2;
+
+    for (int i = 0; i < totalMaxESS.size(); ++i) {
+        if (totalMaxESS.at(i) > 0) {
+            const qreal sf = stableMaxESS.at(i) / static_cast<qreal>(totalMaxESS.at(i));
+            stabFractions0.append(sf);
+            if (totalMaxESS.at(i) >= 2)
+                stabFractions2.append(sf);
+        }
+    }
+    qSort(stabFractions0);
+    qSort(stabFractions2);
+
+
+    // --------
+    for (int p = 10; p <= 100; p += 10) {
+        const int i0 = (stabFractions0.size() - 1) * (p / 100.0);
+        const int i2 = (stabFractions2.size() - 1) * (p / 100.0);
+        stabFracPercentiles_.insert(
+            p, qMakePair(100 * stabFractions0.at(i0), 100 * stabFractions2.at(i2)));
+    }
+}
diff --git a/src/bm/dataqualitystats.h b/src/bm/dataqualitystats.h
new file mode 100644
index 0000000..aa9c8f5
--- /dev/null
+++ b/src/bm/dataqualitystats.h
@@ -0,0 +1,50 @@
+/****************************************************************************
+**
+** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
+** Contact: Qt Software Information (qt-info@nokia.com)
+**
+** This file is part of the BM project on Qt Labs.
+**
+** This file may be used under the terms of the GNU General Public
+** License version 2.0 or 3.0 as published by the Free Software Foundation
+** and appearing in the file LICENSE.GPL included in the packaging of
+** this file.  Please review the following information to ensure GNU
+** General Public Licensing requirements will be met:
+** http://www.fsf.org/licensing/licenses/info/GPLv2.html and
+** http://www.gnu.org/copyleft/gpl.html.
+**
+** If you are unsure which license is appropriate for your use, please
+** contact the sales department at qt-sales@nokia.com.
+**
+** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
+** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
+**
+****************************************************************************/
+
+#ifndef DATAQUALITYSTATS_H
+#define DATAQUALITYSTATS_H
+
+#include "resulthistoryinfo.h"
+#include <QList>
+#include <QMap>
+#include <QPair>
+
+class DataQualityStats {
+public:
+    DataQualityStats(const qreal diffTolerance, const int stabTolerance)
+        : diffTolerance(diffTolerance)
+        , stabTolerance(stabTolerance)
+    {}
+
+    void compute(const QList<ResultHistoryInfo *> &rhInfos);
+    QMap<int, int> totalMaxESSFreq() const { return totalMaxESSFreq_; }
+    QMap<int, QPair<qreal, qreal> > stabFracPercentiles() const { return stabFracPercentiles_; }
+
+private:
+    qreal diffTolerance;
+    int stabTolerance;
+    QMap<int, int> totalMaxESSFreq_;
+    QMap<int, QPair<qreal, qreal> > stabFracPercentiles_;
+};
+
+#endif // DATAQUALITYSTATS_H
diff --git a/src/bm/index.cpp b/src/bm/index.cpp
index f71e0d8..314b369 100644
--- a/src/bm/index.cpp
+++ b/src/bm/index.cpp
@@ -23,6 +23,7 @@
 
 #include "index.h"
 #include "resulthistoryinfo.h"
+#include "dataqualitystats.h"
 #include "bmmisc.h"
 #include <QBitArray>
 #include <QDebug>
@@ -103,7 +104,7 @@ void Index::init(
 
 bool IndexAlgorithm1::computeValues(
     QList<qreal> *values, int *baseValuePos, QList<int> *contrCounts, QString *error,
-    QList<QList<RankedInfo> > *topContr, int topContrLimit) const
+    QList<QList<RankedInfo> > *topContr, int topContrLimit, DataQualityStats *dqStats) const
 {
     if (!isValid()) {
         *error = invalidReason();
@@ -280,35 +281,8 @@ bool IndexAlgorithm1::computeValues(
     }
 
 
-    const bool computeDataQualityStatistics = false; // 4 NOW
-    if (computeDataQualityStatistics) {
-        // Step 1: Compute the MaxESSTotalCount and MaxESSStableCount for each
-        //         contributing RH (compute for the exact median-smoothed
-        //         values that formed the basis for computing the index)
-        //
-        // Step 2: Compute the complete distribution of MaxESSTotalCount
-        //         (note that the number of distinct counts are likely to be only a small
-        //         fraction of the number of RHs):
-        //
-        //           TC(c1) = <# of RHs with a MaxESSTotalCount of c1>
-        //           TC(c2) = <# of RHs with a MaxESSTotalCount of c2>
-        //           ...
-        //           TC(cN) = <# of RHs with a MaxESSTotalCount of cN>
-        //
-        //         (TC = Total Count, and N is number of distinct counts)
-        //          
-        // Step 3: Compute the percentile distribution (for the 10 levels 10%, 20%, ..., 100%)
-        //         of the SF (stability fraction) values (where the SF for a given
-        //         RH is MaxESSStableCount / MaxESSTotalCount):
-        //
-        //           SFP(100) = <the max SF value for the worst 100% of the RHs (i.e. all RHs!)>
-        //           SFP(90)  = <the max SF value for the worst  90% of the RHs>
-        //           SFP(80)  = <the max SF value for the worst  80% of the RHs>
-        //           ...
-        //           SFP(10)  = <the max SF value for the worst  10% of the RHs>
-        //
-        //           (SFP = Stability Fraction Percentile)
-    }
+    if (dqStats)
+        dqStats->compute(rhInfos);
 
     return true;
 }
diff --git a/src/bm/index.h b/src/bm/index.h
index f07e4f0..db0fce7 100644
--- a/src/bm/index.h
+++ b/src/bm/index.h
@@ -28,6 +28,7 @@
 #include <QList>
 
 class ResultHistoryInfo;
+class DataQualityStats;
 
 class Index {
 public:
@@ -59,9 +60,12 @@ public:
     // in \a contrCounts.
     // If non-null, the \a topContr list will upon return contain a list of the \a topContrLimit
     // most significant contributors at each evaluation timestamp.
+    // If non-null, the \a dqStats object will upon return contain data quality statistics for
+    // the contributing result histories.
     virtual bool computeValues(
         QList<qreal> *values, int *baseValuePos, QList<int> *contrCounts, QString *error,
-        QList<QList<RankedInfo> > *topContr = 0, int topContrLimit = -1) const = 0;
+        QList<QList<RankedInfo> > *topContr = 0, int topContrLimit = -1,
+        DataQualityStats *dqStats = 0) const = 0;
 
 protected:
     QList<ResultHistoryInfo *> rhInfos;
@@ -88,7 +92,8 @@ public:
 
     bool computeValues(
         QList<qreal> *values, int *baseValuePos, QList<int> *contrCounts, QString *error,
-        QList<QList<RankedInfo> > *topContr = 0, int topContrLimit = -1) const;
+        QList<QList<RankedInfo> > *topContr = 0, int topContrLimit = -1,
+        DataQualityStats *dqStats = 0) const;
 };
 
 #endif // INDEX_H
diff --git a/src/bm/resulthistoryinfo.cpp b/src/bm/resulthistoryinfo.cpp
index ad13c2c..cb18924 100644
--- a/src/bm/resulthistoryinfo.cpp
+++ b/src/bm/resulthistoryinfo.cpp
@@ -23,6 +23,8 @@
 
 #include "resulthistoryinfo.h"
 #include "bmmisc.h"
+#include <qnumeric.h>
+#include <QDebug>
 
 // Searches for the (zero-based) position of the last non-outlier value at or
 // before \a timestamp. If found, the position is passed in \a pos and the function returns
@@ -107,3 +109,68 @@ void ResultHistoryInfo::markOutliers() const
 
     outliersMarked = true;
 }
+
+// ### 2 B DOCUMENTED!
+static void appendMaxESSStats(int seqSize, int *total, int *stable, int stabTolerance)
+{
+    if (seqSize <= 0)
+        return;
+    (*total)++;
+    if (seqSize >= stabTolerance)
+        (*stable)++;
+}
+
+// ### 2 B DOCUMENTED!
+bool ResultHistoryInfo::equal(int i, int j, int diffTolerance) const
+{
+    if ((i < 0) || (j < 0) || (i >= values.size()) || (j >= values.size()))
+        return false;
+
+    if (i == j)
+        return true;
+
+    const qreal vi = values.at(i);
+    const qreal vj = values.at(j);
+    if (vi == vj)
+        return true;
+
+    const qreal maxRatio = qAbs(qMax(vi, vj) / qMin(vi, vj));
+    if (!qIsFinite(maxRatio))
+        return false;
+
+    return (100 * (maxRatio - 1)) <= diffTolerance;
+}
+
+// ### 2 B DOCUMENTED!
+void ResultHistoryInfo::computeMaxESSStats(
+    qreal diffTolerance, int stabTolerance, int *total, int *stable)
+{
+    *total = *stable = 0;
+
+    int basePos = -1;
+    int seqSize = 0;
+
+    for (int i = 0; i < values.size(); ++i) {
+
+        if (isOutlier(i)) {
+            if (i == values.size() - 1)
+                appendMaxESSStats(seqSize, total, stable, stabTolerance);
+
+        } else {
+
+            ++seqSize;
+
+            if (basePos == -1) {
+                basePos = i;
+            } else if (!equal(basePos, i, diffTolerance)) {
+                appendMaxESSStats(seqSize, total, stable, stabTolerance);
+                seqSize = 1;
+                basePos = i;
+            }
+
+            if (i == values.size() - 1)
+                appendMaxESSStats(seqSize, total, stable, stabTolerance);
+        }
+
+    }
+}
diff --git a/src/bm/resulthistoryinfo.h b/src/bm/resulthistoryinfo.h
index 6cb7366..a65757f 100644
--- a/src/bm/resulthistoryinfo.h
+++ b/src/bm/resulthistoryinfo.h
@@ -69,6 +69,8 @@ public:
     QString testFunction() const { return testFunction_; }
     QString dataTag() const { return dataTag_; }
 
+    void computeMaxESSStats(qreal diffTolerance, int stabTolerance, int *total, int *stable);
+
 private:
     int bmcontextId_;
     QList<int> timestamps_;
@@ -92,6 +94,8 @@ private:
     mutable bool outliersMarked;
     mutable QBitArray outliers;
     void markOutliers() const;
+
+    bool equal(int i, int j, int diffTolerance) const;
 };
 
 #endif // RESULTHISTORYINFO_H
diff --git a/src/bmweb/indexsection.js b/src/bmweb/indexsection.js
index 9623f0f..1947979 100644
--- a/src/bmweb/indexsection.js
+++ b/src/bmweb/indexsection.js
@@ -569,8 +569,7 @@ function IndexSection()
         fieldset = td.appendChild(document.createElement("fieldset"));
         legend = fieldset.appendChild(document.createElement("legend"));
         legend.appendChild(document.createTextNode("Data Quality Statistics"));
-        legend.innerHTML =
-            "Data Quality Statistics<span style=\"color:red\"> (not implemented yet)</span>";
+        legend.innerHTML = "Data Quality Statistics";
         legend.setAttribute("style", "font-size:12");
         table = fieldset.appendChild(document.createElement("table"));
         table.setAttribute("style", "border:0px; padding:0px");