diff --git a/src/batch.rs b/src/batch.rs
index 56a76bb..43872c0 100644
--- a/src/batch.rs
+++ b/src/batch.rs
@@ -80,6 +80,24 @@ impl Event {
             .map(|team| team.output)
             .collect::<Vec<_>>()
     }
+
+    fn within_priors(
+        &self,
+        online: bool,
+        forward: bool,
+        skills: &HashMap<Index, Skill>,
+        agents: &HashMap<Index, Agent>,
+    ) -> Vec<Vec<Player>> {
+        self.teams
+            .iter()
+            .map(|team| {
+                team.items
+                    .iter()
+                    .map(|item| item.within_prior(online, forward, skills, agents))
+                    .collect::<Vec<_>>()
+            })
+            .collect::<Vec<_>>()
+    }
 }
 
 #[derive(Debug)]
@@ -265,6 +283,7 @@ impl Batch {
             .collect::<HashMap<_, _>>()
     }
 
+    // TODO(anders): Remove this function.
     pub(crate) fn within_priors(
         &self,
         event: usize,
@@ -285,13 +304,13 @@ impl Batch {
     }
 
     pub(crate) fn iteration(&mut self, from: usize, agents: &HashMap<Index, Agent>) {
-        for e in from..self.events.len() {
-            let teams = self.within_priors(e, false, false, agents);
-            let result = self.events[e].outputs();
+        for event in self.events.iter_mut().skip(from) {
+            let teams = event.within_priors(false, false, &self.skills, agents);
+            let result = event.outputs();
 
-            let g = Game::new(teams, result, self.events[e].weights.clone(), self.p_draw);
+            let g = Game::new(teams, result, event.weights.clone(), self.p_draw);
 
-            for (t, team) in self.events[e].teams.iter_mut().enumerate() {
+            for (t, team) in event.teams.iter_mut().enumerate() {
                 for (i, item) in team.items.iter_mut().enumerate() {
                     self.skills.get_mut(&item.agent).unwrap().likelihood =
                         (self.skills[&item.agent].likelihood / item.likelihood)
@@ -301,7 +320,7 @@ impl Batch {
                 }
             }
 
-            self.events[e].evidence = g.evidence;
+            event.evidence = g.evidence;
         }
     }
 
@@ -375,9 +394,9 @@ impl Batch {
                 self.events
                     .iter()
                     .enumerate()
-                    .map(|(e, event)| {
+                    .map(|(_, event)| {
                         Game::new(
-                            self.within_priors(e, online, forward, agents),
+                            event.within_priors(online, forward, &self.skills, agents),
                             event.outputs(),
                             event.weights.clone(),
                             self.p_draw,
@@ -400,9 +419,9 @@ impl Batch {
                         .flat_map(|team| &team.items)
                         .any(|item| targets.contains(&item.agent))
                 })
-                .map(|(e, event)| {
+                .map(|(_, event)| {
                     Game::new(
-                        self.within_priors(e, online, forward, agents),
+                        event.within_priors(online, forward, &self.skills, agents),
                         event.outputs(),
                         event.weights.clone(),
                         self.p_draw,
diff --git a/src/history.rs b/src/history.rs
index 1c03dd6..b746b4f 100644
--- a/src/history.rs
+++ b/src/history.rs
@@ -227,7 +227,7 @@ impl History {
     pub fn log_evidence(&mut self, forward: bool, targets: &[Index]) -> f64 {
         self.batches
             .iter()
-            .map(|batch| batch.log_evidence(self.online, targets, forward, &mut self.agents))
+            .map(|batch| batch.log_evidence(self.online, targets, forward, &self.agents))
             .sum()
     }