diff --git a/yoshimi-testrunner/src/util/data.hpp b/yoshimi-testrunner/src/util/data.hpp
index f3e0b3e12..8dd3d7589 100644
--- a/yoshimi-testrunner/src/util/data.hpp
+++ b/yoshimi-testrunner/src/util/data.hpp
@@ -253,6 +253,17 @@ public:
                 });
     }
 
+    void dropLastRow()
+    {
+        if (not empty())
+            forEach(TAB::allColumns(),
+                [](auto& col)
+                {
+                    size_t siz = col.data.size();
+                    col.data.resize(siz>0? siz-1 : 0);
+                });
+    }
+
     void reserve(size_t expectedCapacity)
     {
         forEach(TAB::allColumns(),
@@ -282,6 +293,7 @@ public:
                 fs::rename(filename_, oldFile);
         }
         fs::rename(newFilename, filename_);
+        filename_ = consolidated(filename_); // lock onto absolute path
     }
 
 
diff --git a/yoshimi-testrunner/src/util/regex.hpp b/yoshimi-testrunner/src/util/regex.hpp
index 1aae85bc0..169a75b55 100644
--- a/yoshimi-testrunner/src/util/regex.hpp
+++ b/yoshimi-testrunner/src/util/regex.hpp
@@ -32,9 +32,12 @@
 
 #include <regex>
 #include <string>
+#include <optional>
 
 namespace util {
 
+using std::regex;
+using std::smatch;
 using std::string;
 
 
@@ -43,7 +46,7 @@ using std::string;
 struct MatchSeq
     : std::sregex_iterator
 {
-    MatchSeq(string const& toParse, std::regex const& regex)
+    MatchSeq(string const& toParse, regex const& regex)
         : std::sregex_iterator{toParse.begin(), toParse.end(), regex}
     { }
 
@@ -53,5 +56,32 @@ struct MatchSeq
 };
 
 
+
+/** encapsulated regex buildable from string */
+class Matcher
+{
+    std::optional<regex> pattern_;
+
+public:
+    Matcher()  = default;
+    Matcher(string const& regexDefinition)
+        : pattern_{regexDefinition.empty()? std::nullopt
+                                          : std::make_optional<regex>(regexDefinition, regex::optimize)}
+    { }
+    // standard copy acceptable
+
+    explicit operator bool()  const
+    {
+        return bool(pattern_);
+    }
+
+    bool matchesWithin(string probe)  const
+    {
+        return pattern_? std::regex_search(probe, *pattern_)
+                       : true; // undefined pattern matches everything
+    }
+};
+
+
 }//(End)namespace util
 #endif /*TESTRUNNER_UTIL_REGEX_HPP_*/
diff --git a/yoshimi-testrunner/src/util/statistic.hpp b/yoshimi-testrunner/src/util/statistic.hpp
index 80c1a12d7..c2ab6bb96 100644
--- a/yoshimi-testrunner/src/util/statistic.hpp
+++ b/yoshimi-testrunner/src/util/statistic.hpp
@@ -243,7 +243,7 @@ inline auto computeLinearRegression(DataSpan<RegressionPoint> const& points)
     double socket   = ym - gradient * xm;                           // Regression line:  Y-ym = gradient · (x-xm)  ; set x≔0 yields socket
 
     // Correlation (Pearson's r)
-    double correlation = wyysum==0.0? 0.0 : gradient * sqrt(varx/vary);
+    double correlation = wyysum==0.0? 1.0 : gradient * sqrt(varx/vary);
 
     // calculate error Δ for all measurement points
     size_t n = points.size();
@@ -304,7 +304,7 @@ inline auto computeTimeSeriesLinearRegression(DataSpan<D> const& series)
     double socket   = ym - gradient * im;      // Regression line:  Y-ym = Gradient · (i-im)  ; set i≔0 yields socket
 
     // Correlation (Pearson's r)
-    double correlation = yysum==0.0? 0.0 : gradient * sqrt(varx/vary);
+    double correlation = yysum==0.0? 1.0 : gradient * sqrt(varx/vary);
     return make_tuple(socket,gradient,correlation);
 }