Refactor error calculation in Plot and ConfidenceIndices; update index delimiter in SimulationBuilder

src/main/java/net/berack/upo/valpre/Plot.java

@@ -144,8 +144,7 @@ public class Plot {
 
             var model = this.statList.getModel();
             var avg = summary.average;
-            var err = summary.calcError(0.95)
+            var err = summary.calcError(0.95);
-                    .apply(val -> val / 2); // Done to get the error for the mean value
 
             for (int i = 0; i < model.getSize(); i++) {
                 var entry = model.getElementAt(i);

src/main/java/net/berack/upo/valpre/SimulationBuilder.java

@@ -201,7 +201,7 @@ public class SimulationBuilder {
         if (indices == null)
             return this;
 
-        for (var index : indices.split(",")) {
+        for (var index : indices.split(";")) {
             var parts = index.split("=");
             if (parts.length != 2)
                 throw new IllegalArgumentException("Invalid confidence index: " + index);

src/main/java/net/berack/upo/valpre/sim/ConfidenceIndices.java

@@ -138,7 +138,7 @@ public class ConfidenceIndices {
 
             for (var stat : statistics) {
                 var err = error.of(stat);
-                if (!Double.isFinite(err))
+                if (!Double.isFinite(err) || err == 0.0d)
                     continue;
 
                 retValues.add("%s:%s=%.3f".formatted(this.nodes[i], stat, err));

src/main/java/net/berack/upo/valpre/sim/stats/NodeStats.java

@@ -298,7 +298,8 @@ public class NodeStats implements Cloneable, Iterable<Double> {
         public NodeStats calcError(NodeStats alpha) {
             var n = this.stats.size();
             var distr = new TDistribution(null, n - 1);
-            var tValue = alpha.clone().apply(a -> distr.inverseCumulativeProbability(a));
+            var prob = alpha.clone().apply(a -> 1 - (1 - a) / 2.0d);
+            var tValue = prob.apply(p -> distr.inverseCumulativeProbability(p));
 
             return this.stdDev().merge(tValue, (std, t) -> t * (std / Math.sqrt(n)));
         }