Before revision:  However, once we controlled for data sparsity in our second reference model , we found that measures from the observed data then fell within the range of those from the reference model which showed that this result may have been due to the unequal frequencies of each observed behavior.
After revision:  However, once we controlled for data sparsity , we found that measures from the observed data then fell within the range of those from the reference model which showed that this result may have been due to the unequal frequencies of each observed behavior.