Chap.3 Analysis of Accounting Transactions
audit precedures and accounting cycle
- Audit Procedures and Accounting Cycles :
- Audits are structured around accounting cycles due to economies of scale and better transaction tracking.
- Substantive Year-End Tests 1 : Income statement accounts are transaction-based, requiring knowledge of cycles for accurate estimation.
- PCAOB Guidance for Audit Stages :
- Planning and Risk Assessment :
- Use audit risk assessment to identify high-risk transactions and set audit scope, budget, and tests.
- Interim Compliance Tests (運用評価手続) :Mid-year tests focus on high-risk transactions.
- Attribute Sampling 1 : For high-risk areas;
- Discovery Sampling 2 : To check for possible high error rates.
Substantive Testing and Technology in Audits
- Substantive Tests : - Final phase focused on testing financial report balances for material errors based on interim test findings. - Expands testing of trial balance monetary accounts based on discovered error rates.
- Technology in Audits :
- Computer-Based Auditing :
- Data Retention :
- Key Skills :
The Origin of Accounting Transactions
- Classification and GAAP Compliance :
- Chart of Accounts : Custom categories for transaction classification, enabling comparison across firms and adhering to GAAP.
- High-volume transactions have dedicated journals.
- The “Transaction Stream” : Real-world events filtered through capture, legal, boundary, classification, and GAAP layers to ensure informative, comparable financial statements.
Audit Tests as Learning Models
Audit Evidence Collection Sequence
- Audit Planning : Defines scope and sample size.
- Error Identification : If errors are found, additional evidence is collected to estimate the error rate in the transaction flow.
- Control Assessment : Transaction flows with intolerable error rates are documented in the Internal Control Memo at the end of the interim compliance audit.
- Year-End Testing Adjustment : Affected accounts in financial statements undergo increased sample testing to ensure accurate material error detection.
Working with Dates
- Time is an essential component of auditing.
- Income statement accounts represent sums of transactions within strictly set periods, and balance sheet accounts are stated at a specific time.
- The
lubridate package makes it easier to do the things R does with date-times and possible to do the things that Base-R does not.
後半で実践します。
Accounting Transactions
- Definition of Accounting Transactions :
- Represent economic events that impact firm wealth.
- Recorded in Journal Entries : Specialized journals for high-volume transactions.
- Historical Evolution :
- Pre-20th Century : firm wealth.
- Modern Focus : managerial performance and stakeholder interests.
- Resolution and Sampling :
- Transactions recorded with a minimum resolution of one dollar.
- Financial reports may aggregate data to thousands or millions.
- Characteristics of Transaction Distributions :
- Left-Bounded at Zero : Contra-accounts record reductions without negative values.
- Zero-Inflated : Presence of non-impacting transactions (estimates, adjustments).
- Multimodal : Caused by independent processes, unit price multiplied by quantity, or other factors.
Sampling Assumptions
- Central Limit Theorem (CLT) in Accounting :
- Assumes that errors are Normally distributed (正規分布) when sampling due to summation reliance in accounting.
- Caution : Auditors should not rely solely on CLT; normality assumptions may be inappropriate for error identification.
- Extreme Value Theory for Upper Tail Analysis :
- Focus on Material Misstatements (重要な虚偽表示): Audit decisions prioritize the upper tail (extreme values) of distributions.
Couching Institutional Language in Statistical Terms
- Sampling Risks in Auditing :
- Risk of Assessing Control Risk is :
- Too Low : type II error.
- Too High : type I error.
- Substantive Tests (実証手続) :
- Risk of Incorrect Acceptance : type II error.
- Risk of Incorrect Rejection : type I error.
- Audit Risk Model :
- Formula : AR = IR \times CR \times DR
- Inherent Risk (IR) : Risk within transactions.
- Control Risk (CR) : Risk of undetected misstatements due to internal control weaknesses.
- Detection Risk (DR) : Risk that audit procedures fail to detect material errors.
- Audit Objectives :
- Fairness : Assurance of material error absence.
- Efficiency : Cost-effective data collection and analysis.
Market Efficiency and Analytical Procedures
- Market-Based Evidence :
- Efficient Markets Hypothesis (EMH)
- Capital Asset Pricing Model (CAPM)
- Benefits of Market-Based Analytical Procedures :
- Provides information-rich insights without extensive fieldwork.
- Potentially substitutes for increased audit scope or risk reduction.
- Gaussian Assumptions in Audits :
- Gaussian distributions are assumed for practicality and efficiency.
Transaction Samples and Populations
- Purpose of Sampling : Controls audit costs by examining a subset of transactions relevant to the audit.
- Population vs. Sample :
- Population: All relevant transactions.
- Sample: A small, representative subset.
- Sampling Methods :
- Monetary Unit Sampling : Uses dollars as sample units for year-end substantive testing to detect material errors in a/c balances.
- Transaction/Record Sampling : Uses individual transactions as sample units for internal control testing prior to year-end.
Sampling Guidelines
The AICPA provides guidelines on sampling in several standards:
These discuss several approaches to the audit sampling process.
- Statistical audit
- Non-statistical audit
- Monetary unit sampling
- Attribute sampling
- Multi-location sampling considerations
Types of Sampling
The AICPA discusses the following types of sampling in drawing conclusions from audit evidence.
- Judgmental sampling
- Random sampling
- Fixed-interval sampling
- Random-interval sampling
- Conditional sampling
- Stratified sampling
- Transaction or Record sampling
- Monetary Unit Sampling
- Estimation sampling
- Acceptance sampling
- Discovery sampling
Accounting Cycles
- An accounting cycle begins when accountants create a transaction from a source document and ends with the completion of the financial reports and closing of temporary accounts in preparation for a new cycle.
- Revenue cycle.
- Expenditure cycle
- Conversion cycle (Production cycle).
- Financing (Capital Acquisition and repayment).
- Fixed assets.
Substantive Test
- The purpose of substantive procedures is to provide audit evidence as to the completeness, accuracy, and validity of the information contained in the accounting records or in the F/S.
- Substantive testing examines account balances to assess accuracy and materiality of errors.
- The scope of testing depends on the effectiveness of internal controls.
- Statistical sampling is used to estimate total error or set confidence limits for errors in accounts.
Important Concepts in Probability and Statistics
- Probability distributions are models describing the variability of data or the underlying population from which the data is drawn.
- There are perhaps 50 or 60 different distributions that are used in characterizing population statistics, but only half a dozen are commonly used.
- Quite often when we refer to parametric statistics, we are making an assumption of Normal (Gaussian) distributions for the data.
- We will see later that this assumption may not be warranted for accounting and financial transactions.
- Normal (Gaussian) distribution : The bell-shaped normal distribution is iconic in traditional statistics. Related terms are:
- Standardization : Subtract the mean and divide by the standard deviation.
- z-score : The result of standardizing an individual data point.
- Standard normal : A normal distribution with
mean = 0 and standard deviation = 1.
- QQ-Plot : A quantile (of the sample) by quantile (of a Normal distribution) plot to visualize how close a sample distribution is to a Normal distribution.
various distributions
- Normal Dist.
- Binomial Dist.
- Bernoulli Dist.
- Poisson Dist.
each distributions have density and cumulative distribution.
Logit Model
- Since the dependent variable is dichotomous (binary), results can be improved by using a logit model (from the built-in glm function).
- The following example also showcases R’s analysis of the residual errors (differences between the dependent variable values, and the estimated model on the right-hand side).
- Leverage and distance provide measures of how particular transactions influence the estimation, and are important in identifying outliers.
Machine Learning Methods
- Inference is a decision \delta (estimation, prediction) based on data x \in X that hopefully contains information about a particular set of constructs. Inference may be about:
- Classification — e.g., identifying faces, threats.
- Estimation — e.g., a vector \theta = \{\theta_1, \dots , \theta_n\}.
- Other decisions that may or may not be carried out in real time; e.g., driving a car.