Index: /trunk/ippScripts/scripts/phase0exp.pl
===================================================================
--- /trunk/ippScripts/scripts/phase0exp.pl	(revision 8550)
+++ /trunk/ippScripts/scripts/phase0exp.pl	(revision 8551)
@@ -130,5 +130,9 @@
 	$stats->add_data(@backgrounds);
 	$command .= " -" . PHASE0_BG() . " " . $stats->mean();
-	$command .= " -" . PHASE0_BG_STDEV() . " " . $stats->standard_deviation();
+	if (scalar @backgrounds == 1) {
+	    $command .= ' -' . PHASE0_BG_STDEV() . " 0.0";
+	} else {
+	    $command .= " -" . PHASE0_BG_STDEV() . " " . $stats->standard_deviation();
+	}
     }
     {