code: def compute_within_collection_interval_duration(self, prefix):
          
  
          interstices = []
          for cluster in self.collection_list:
              # Make sure cluster is not a singleton
              if len(cluster) > 1:
                  for i in range(len(cluster)):
                      if i != len(cluster) - 1:
                          interstice = cluster[i+1].start_time - cluster[i].end_time
                          interstices.append(interstice)
  
          self.measures[prefix + 'within_collection_interval_duration_mean'] = get_mean(interstices) \
              if len(interstices) > 0 else 'NA'
  
          if not self.quiet:
              print "Mean within-" + self.current_similarity_measure + "-" + self.current_collection_type + \
                    " between-word duration:", self.measures[prefix + 'within_collection_interval_duration_mean']
docs: Calculates mean between-word duration WITHIN collections.
  
          :param str prefix: Prefix for the key entry in self.measures.
  
          Calculates the mean time between the end of each word in the collection
          and the beginning of the next word.  Note that these times do not necessarily
          reflect pauses, as collection members could be separated by asides or other noises.
  
          Adds the following measures to the self.measures dictionary:
              - TIMING_(similarity_measure)_(collection_type)_within_collection_interval_duration_mean