Task: Classify by type of audit evidence: (1) directly from outsiders, (2) indirectly from outsiders, (3) internal but validated externally, and (4) entirely internal.
1. Bank statement sent directly to the auditor by the bank.
2. Bank statement obtained from client's files.
3. Vendor invoice in client's unpaid voucher file.
4. Duplicate customer invoices in filled order file.
5. Time cards in payroll department files.
6. Credit memo in customer's account file.
7. Material requisitions filed in stock room.
8. Creditor's outstanding balance statement in client's files.
9. Management spreadsheets documenting accounting estimates.
10. Cleared checks returned with bank statement in (1) above.
11. Memo from collection agency on collectibility of a customer's balance.
12. Authorization from treasurer to write-off a customer's account.
Rank these four in terms of least to most persuasive evidence (quality of evidence).