Index: trunk/ippScripts/scripts/detrend_norm_exp.pl
===================================================================
--- trunk/ippScripts/scripts/detrend_norm_exp.pl	(revision 9505)
+++ trunk/ippScripts/scripts/detrend_norm_exp.pl	(revision 9524)
@@ -65,5 +65,5 @@
 {
     my @backgrounds;		# Array of backgrounds in each component
-    my @stdevs;			# Array of standard deviations in each component
+    my @variances;    # Array of variances for each component
     foreach my $file (@$files) {
 	die "Unable to find class id\n" unless defined $file->{class_id};
@@ -72,5 +72,5 @@
 	die "Unable to find bg_mean_stdev for class_id=$class_id\n" unless defined $file->{bg_mean_stdev};
 	push @backgrounds, $file->{bg};
-	push @stdevs, $file->{bg_mean_stdev};
+	push @variances, $file->{bg_stdev}**2;
     }
 
@@ -79,14 +79,10 @@
 	$stats->add_data(@backgrounds);
 	$bg = $stats->mean();
-	if (scalar @backgrounds == 1) {
-	    $bg_stdev = 0.0;
-	} else {
-	    $bg_stdev = $stats->standard_deviation();
-	}
+	$bg_mean_stdev = $stats->standard_deviation() || 0.0;
     }
     {
 	my $stats = Statistics::Descriptive::Sparse->new; # Statistics calculator
-	$stats->add_data(@stdevs);
-	$bg_mean_stdev = $stats->mean();
+	$stats->add_data(@variances);
+	$bg_stdev = sqrt( $stats->mean() );
     }
 }
Index: trunk/ippScripts/scripts/detrend_process_exp.pl
===================================================================
--- trunk/ippScripts/scripts/detrend_process_exp.pl	(revision 9505)
+++ trunk/ippScripts/scripts/detrend_process_exp.pl	(revision 9524)
@@ -61,5 +61,5 @@
 {
     my @backgrounds;		# Array of backgrounds in each component
-    my @stdevs;			# Array of standard deviations in each component
+    my @variances;    # Array of variances for each component
     foreach my $file (@$files) {
 	die "Unable to find class id\n" unless defined $file->{class_id};
@@ -68,5 +68,5 @@
 	die "Unable to find bg_mean_stdev for class_id=$class_id\n" unless defined $file->{bg_mean_stdev};
 	push @backgrounds, $file->{bg};
-	push @stdevs, $file->{bg_mean_stdev};
+	push @variances, $file->{bg_stdev}**2;
     }
 
@@ -75,14 +75,10 @@
 	$stats->add_data(@backgrounds);
 	$bg = $stats->mean();
-	if (scalar @backgrounds == 1) {
-	    $bg_stdev = 0.0;
-	} else {
-	    $bg_stdev = $stats->standard_deviation();
-	}
+	$bg_mean_stdev = $stats->standard_deviation() || 0.0;
     }
     {
 	my $stats = Statistics::Descriptive::Sparse->new; # Statistics calculator
-	$stats->add_data(@stdevs);
-	$bg_mean_stdev = $stats->mean();
+	$stats->add_data(@variances);
+	$bg_stdev = sqrt( $stats->mean() );
     }
 }
Index: trunk/ippScripts/scripts/detrend_reject_exp.pl
===================================================================
--- trunk/ippScripts/scripts/detrend_reject_exp.pl	(revision 9505)
+++ trunk/ippScripts/scripts/detrend_reject_exp.pl	(revision 9524)
@@ -59,5 +59,4 @@
 my @means;			# Array of means
 my @variances;			# Array of variances
-my @meanStdevs;			# Array of mean stdevs
 my @accept;			# Array of accept flags
 my @include;			# Array of include flags
@@ -71,6 +70,5 @@
     push @expTags, $exposure->{exp_tag};
     push @means, $exposure->{bg};
-    push @variances, ($exposure->{bg_stdev}*$exposure->{bg_stdev});
-    push @meanStdevs, $exposure->{bg_mean_stdev}; ### XXX are we keeping this or stdev(mean)?
+    push @variances, $exposure->{bg_stdev}**2;
     push @accept, $exposure->{accept};
     push @include, $exposure->{include};
@@ -80,6 +78,4 @@
 my $varianceStats = Statistics::Descriptive::Sparse->new(); # Statistics calculator
 $varianceStats->add_data(@variances);
-my $meanStdevStats = Statistics::Descriptive::Sparse->new(); # Statistics calculator
-$meanStdevStats->add_data(@meanStdevs);
 
 $ipprc->define_camera($camera);
Index: trunk/ippScripts/scripts/phase0_exp.pl
===================================================================
--- trunk/ippScripts/scripts/phase0_exp.pl	(revision 9505)
+++ trunk/ippScripts/scripts/phase0_exp.pl	(revision 9524)
@@ -100,5 +100,5 @@
 }
 my @backgrounds;                # Array of backgrounds
-my @stdevs;                        # Array of background standard deviations\
+my @variances;                        # Array of background standard deviations\
 my $obsType;                        # Observation type
   
@@ -124,5 +124,5 @@
     
     my $stdev = get_value($imfile, PHASE0_BG_MEAN_STDEV());
-    push @stdevs, $stdev;
+    push @variances, $stdev**2;
 }
 
@@ -147,15 +147,11 @@
         my $stats = Statistics::Descriptive::Sparse->new; # Statistics calculator
         $stats->add_data(@backgrounds);
-	push @command, ( '-' . PHASE0_BG() ), $stats->mean(), ( '-' . PHASE0_BG_STDEV() );
-        if (scalar @backgrounds == 1) {
-	    push @command, 1;
-        } else {
-	    push @command, $stats->standard_deviation();
-        }
+	push @command, ( '-' . PHASE0_BG() ), $stats->mean();
+	push @command, ( '-' . PHASE0_BG_MEAN_STDEV() ), ( $stats->standard_deviation() || 0 )
     }
     {
         my $stats = Statistics::Descriptive::Sparse->new; # Statistics calculator
-        $stats->add_data(@stdevs);
-	push @command, ( '-' . PHASE0_BG_MEAN_STDEV() ), $stats->mean();
+        $stats->add_data(@variances);
+	push @command, ( '-' . PHASE0_BG_STDEV() ), sqrt( $stats->mean() );
     }
     
Index: trunk/ippScripts/scripts/phase3.pl
===================================================================
--- trunk/ippScripts/scripts/phase3.pl	(revision 9505)
+++ trunk/ippScripts/scripts/phase3.pl	(revision 9524)
@@ -59,5 +59,5 @@
 {
     my @backgrounds;		# Array of backgrounds in each component
-    my @stdevs;			# Array of standard deviations in each component
+    my @variances;		# Array of variances for each component
 #    my @ra;			# Array of ra errors
 #    my @dec;			# Array of dec errors
@@ -72,5 +72,5 @@
 #	die "Unable to find zp for class_id=$class_id\n" unless defined $file->{zp};
 	push @backgrounds, $file->{bg};
-	push @stdevs, $file->{bg_mean_stdev};
+	push @variances, $file->{bg_stdev}**2;
     }
 
@@ -79,14 +79,10 @@
 	$stats->add_data(@backgrounds);
 	$bg = $stats->mean();
-	if (scalar @backgrounds == 1) {
-	    $bg_stdev = 0.0;
-	} else {
-	    $bg_stdev = $stats->standard_deviation();
-	}
+	$bg_mean_stdev = $stats->standard_deviation() || 0.0;
     }
     {
 	my $stats = Statistics::Descriptive::Sparse->new; # Statistics calculator
-	$stats->add_data(@stdevs);
-	$bg_mean_stdev = $stats->mean();
+	$stats->add_data(@variances);
+	$bg_stdev = sqrt( $stats->mean() );
     }
 }