Identify whether the following tests are substantive analytical procedures, tests of details of transactions or tests of details of account balances:
1) Test a sample of purchase requisitions for proper authorization.
2) Test transactions around year-end to determine if they are recorded in the proper period.
3) Review results of confirmation of selected accounts payable.
4) Compare payables turnover to previous years' data.
5) Obtain selected vendors' statements and reconcile to vendor accounts.
6) Compare purchase returns and allowances as a percentage of revenue or cost of sales to industry data.