diff --git a/summary_statistics.py b/summary_statistics.py
index 95d6aedcd398da672db50bb12bd1dccab7d1522e..9d0b0ff10448fca2463708c730b56abece1ddd1a 100644
--- a/summary_statistics.py
+++ b/summary_statistics.py
@@ -438,6 +438,7 @@ def do_sum_stats(scenario_dir, name_id, size_chr=2e6,
     all_sfs2["i_xi_norm"] = all_sfs2.i_xi / all_sfs2.i_xi.mean()
     all_sfs2["freq_indiv"] = all_sfs2.index / n_indiv
     all_sfs2["i_xi_sem_norm"] = all_sfs.groupby("N_indiv").i_xi.sem() / all_sfs2.i_xi.mean()
+    all_sfs2["i_xi_std_norm"] = all_sfs.groupby("N_indiv").i_xi.std() / all_sfs2.i_xi.mean()
     all_sfs2["sim_id"] = sim_id
     all_sfs2["scenario"] = scenario
     all_sfs2["label"] = label