According to Generally Accepted Auditing Standards,the Relevant Aspects of a Control

According to generally accepted auditing standards,the relevant aspects of a control system over the preparation of accounting estimates include:
 Identifying where accounting estimates are required.
 Gathering relevant,sufficient,and reliable data for the estimates.
 Developing assumptions about the estimates.
 Preparation of estimates by qualified personnel.
 Adequate review and approval by appropriate levels of authority.
 Comparison of previous estimates with actual results.
 Consideration by management of whether the accounting estimates are reasonable and consistent with the company's operational plans.
Required:
A)How would the auditor test controls over the preparation of accounting estimates?
B)What substantive audit procedures could the auditor use in testing the estimates?