The standard of living in a country can be measured by various indicators. However, the most commonly used indicator is per capita income. Per capita income refers to the average income earned by the citizens of a country in a particular period, usually a year. It is calculated by dividing the total national income by the total population of the country.

Importance of per capita income as an indicator of standard of living:

1. Reflects economic well-being: Per capita income is a good indicator of the economic well-being of a country. A higher per capita income indicates that the citizens of the country are earning more, which translates into better access to goods and services.

2. Reflects quality of life: The standard of living of a country is directly linked to the quality of life of its citizens. A higher per capita income means that citizens can afford better healthcare, education, and housing, which contribute to a better quality of life.

3. Facilitates international comparisons: Per capita income is used to compare the standard of living of different countries. This is because it is a universal indicator that is used worldwide, making it easier to compare the standard of living of countries.

Limitations of per capita income as an indicator of standard of living:

1. Ignores income distribution: Per capita income does not take into account the distribution of income within a country. A country with a high per capita income may still have a high level of poverty and income inequality.

2. Ignores non-monetary factors: Per capita income does not consider non-monetary factors such as access to healthcare, education, and social services. These factors are also important in determining the standard of living of a country.

In conclusion, per capita income is one of the most commonly used indicators for measuring the standard of living in a country. While it has its limitations, it is a useful tool for assessing the economic well-being and quality of life of a country's citizens.