ISA200 Objective and General Principles Governing an Audit of Financial Statements states that the auditors should carry out an audit in accordance with ISAs and ethical principles, so as to provide reasonable assurance that the financial statements are free from material misstatement.
　　Reasonable assurance is subject to various factors:
　　·The inherent limitations of the audit process which arise from the use of sample-based testing；
　　·The inherent limitations of any accounting or internal control system；
　　·The fact that most evidence is persuasive rather than conclusive – a significant element of any audit involves the use of judgment and the auditor must normally take various documents and explanations at face value；
　　Auditing principle
　　The auditor should plan and perform the audit with an attitude of professional skepticism recognizing that circumstances may exist which cause the financial statements to be materially misstated.
　　Extent of audit work
　　It is for auditors to decide on the extent of audit work they consider necessary in order to support their opinion. They may decide to conduct an extensive review of the accounting systems by carrying out detailed tests on a large number of transactions, documents, records, etc. On the other hand, they may wish to rely on the internal controls which are operation to justify a reduction in the level of audit testing on those items.
　　Audit Risk
　　The ways in which risk models are used can be linked to the objectives of the audit.
　　·External auditors are principally concerned with the risk that the financial statements contain material misstatements that they may not detect.
　　·Internal auditors are concerned with the risks that the organization will not achieve its objectives and hence will consider all the risks that could be financial, operational, or compliance in nature.

责任编辑：虫虫