CASE:You are completing the audit of Curzon Pty Ltd. You read a note in the file from your assistant, Joe Burns, which states,

"I selected a sample of 20 entries in the Sales Journal and vouched them to the supporting documentation (corresponding Shipping Order and Sales Order). I found no errors, so concluded that the controls over the occurrence assertion for sales were effective".

QUESTION

Is Joe justified in forming the conclusion that he did? Give the reason for your answer.