diff --git a/image_analysis/scale_merge/RotationScaleMerge.cpp b/image_analysis/scale_merge/RotationScaleMerge.cpp
index b95fac06b..39db29683 100644
--- a/image_analysis/scale_merge/RotationScaleMerge.cpp
+++ b/image_analysis/scale_merge/RotationScaleMerge.cpp
@@ -4088,13 +4088,15 @@ RotationScaleMerge::Result RotationScaleMerge::MergeAndStats(int n_groups, bool
     //      grid_d_max, and the completeness denominator is enumerated over exactly that. The fulls
     //      hold every group that was ingested, cut or not, so a grid reaching past the cut needs
     //      d_floor - the cut, as the erase above applied it, by group d - to keep the observations
-    //      of the groups the run did not keep out of every count; the run's own grid ends at the
-    //      finest kept reflection and needs none. ----
+    //      of the groups the run did not keep out of every count. The run's own grid needs it too:
+    //      it bottoms 0.1% below the finest kept reflection, and the groups in that band were erased
+    //      from the merge, so without the floor they would count in N_obs and R_meas but not in
+    //      N_uniq. ----
     const int n_shells = report_shell_count;
     struct AnomExport { float Ip = NAN, sIp = NAN, Im = NAN, sIm = NAN; };
     std::unordered_map<uint64_t, AnomExport> anom_export;   // filled by the run's own table only
     auto statistics_over = [&](const std::vector<MergedReflection> &merged, float grid_d_min,
-                               float grid_d_max, float d_max_label, float d_floor,
+                               float grid_d_max, float d_max_label, double d_floor,
                                bool own_table) -> MergeStatistics {
         ResolutionShells shells(grid_d_min, grid_d_max, n_shells);
         const auto shell_mean_1_d2 = shells.GetShellMeanOneOverResSq();
@@ -4369,7 +4371,8 @@ RotationScaleMerge::Result RotationScaleMerge::MergeAndStats(int n_groups, bool
     // The innermost shell is labelled by the bound it reaches, except when that bound is infinite
     // and the coarsest reflection measured is the only finite thing to say.
     const float d_max_label = std::isfinite(d_max_declared) ? d_max_declared : sd_max;
-    result.statistics = statistics_over(result.merged, d_min_pad, d_max_declared, d_max_label, 0.0f, true);
+    result.statistics = statistics_over(result.merged, d_min_pad, d_max_declared, d_max_label,
+                                        effective_d_min.value_or(0.0), true);
     MergeStatistics &out = result.statistics;
     out.overall.d_min = sd_min; out.overall.d_max = sd_max;
 
@@ -4398,7 +4401,7 @@ RotationScaleMerge::Result RotationScaleMerge::MergeAndStats(int n_groups, bool
             in_min = std::min(in_min, m.d); in_max = std::max(in_max, m.d);
         }
         MergeStatistics ref = statistics_over(result.merged, d_lo, d_hi, std::isfinite(d_hi) ? d_hi : in_max,
-                                              static_cast<float>(effective_d_min.value_or(0.0)), false);
+                                              effective_d_min.value_or(0.0), false);
         ref.overall.d_min = in_min < in_max ? in_min : 0.0f;
         ref.overall.d_max = in_max;
         result.reference_statistics = std::move(ref);