In national income accounting, which one of the following is NOT recognised as a standard method of estimating a country's national income?

Introduction / Context:
National income accounting is a fundamental topic in macroeconomics. To measure the total income or output of an economy, economists use well established methods that follow clear definitions and accounting identities. Competitive exams often test whether candidates can distinguish between these standard methods and fictitious or incorrect ones. This question asks you to identify which option is not a recognised method of estimating national income in standard macroeconomic theory.

Given Data / Assumptions:

• The subject is methods of estimating national income.
• Options include expenditure method, output method, income method, and matrix method.
• We assume the basic textbook understanding of GDP and national income calculation.
• Each standard method should correspond to a real, widely taught approach in economics.

Concept / Approach:
There are three commonly recognised methods of calculating national income or GDP: the output (or product) method, the income method, and the expenditure method. The output method sums the value of final goods and services produced; the income method sums all factor incomes such as wages, rent, interest and profit; and the expenditure method sums all final expenditures by households, firms, government, and net exports. A "matrix method" is not a standard term or method in national income accounting; it does not appear in basic textbooks as a recognised approach to calculate GDP or national income. Therefore, "Matrix method" is the correct answer as the one that is not a method of estimating national income.

Step-by-Step Solution:

Verification / Alternative check:
Any standard Indian economics textbook or national income accounting guide will describe the three methods—output, income and expenditure—often with diagrams or tables. None of them mention a "matrix method" as a separate category. While matrices can be used as mathematical tools in input output analysis or in presenting data, there is no formal method of estimating national income called the matrix method. This absence in core literature confirms that matrix method is the incorrect one in the list.

Why Other Options Are Wrong (they are valid methods):

• Expenditure method: A fully recognised method that adds up consumption, investment, government expenditure, and net exports to calculate GDP.
• Output method: Also known as the product method, it measures GDP by summing the value of final goods and services produced in an economy.
• Income method: Another standard method that calculates national income by adding up all factor incomes earned during production.

Common Pitfalls:
Some candidates may be tempted by unfamiliar terms and think that "matrix method" could be an advanced technique they have not encountered yet. Others might mistake different names for the same method and incorrectly doubt the output or income method. To avoid such errors, remember that the three core methods are universally accepted and appear in almost every basic macroeconomics text. Any fourth option with a novel name in this context is likely to be the incorrect one.

Final Answer:
The option that is not a recognised method of estimating national income is the Matrix method.