diff --git a/script/jitter_scan.py b/script/jitter_scan.py
index 8c189b8..09eba61 100644
--- a/script/jitter_scan.py
+++ b/script/jitter_scan.py
@@ -194,7 +194,7 @@ vsum_jit_amplt = all_statistics_data()
 vsum_jit_phase = all_statistics_data()
 
 # calculate statistics
-ref_jit_amplt = all_statistics_calc(scan_result.getReadable(0))
+ref_jit_amplt = all_statistics_calc(scan_result.getReadable(self,0))
 ref_jit_phase = all_statistics_calc(scan_result.getReadable(1))
 
 iqm_jit_amplt = all_statistics_calc(scan_result.getReadable(2))