Stocks and flows

Goods available in the warehouse in the morning represent inventory existing at a particular point of time, so they are a stock. Goods dispatched during the day are measured by the quantity moved over a period of time, so they are a flow. The time reference in each phrase makes the distinction clear. Therefore, option A is correct.

Cash holdings today are measured at a particular point of time, so they are a stock. A stock records the amount possessed at a given date. Cash payments made during the week are accumulated over a period and represent transactions occurring through that interval, so they are a flow. Thus, the correct answer is stock and flow, or option A.

Investment adds new productive assets to the existing capital stock, while depreciation removes part of the value of existing capital. Net investment equals gross investment minus depreciation. If investment is greater than depreciation, net investment is positive and the capital stock increases. Thus option B is correct.

Saving made during a day, month, or year is normally a flow because it is measured over a period. However, the total accumulated saving existing on a specified date is a stock-like amount because it is measured at a point in time. Therefore, option D correctly describes the stock presentation of saving.

GDP measures the value of final goods and services produced during one year, so it is a flow variable. National wealth is the total value of assets available at the end of the year, a particular point in time, so it is a stock variable. Hence the answer is flow and stock.

The number of unemployed persons on a specified date is measured at one point in time, so it is a stock variable. The number of people obtaining jobs during the year is counted over a period, so it is a flow variable. Therefore, the correct order is stock and flow.

A point-of-time quantity is measured on a specific date, while a period-of-time quantity is measured over an interval. Year-end inventory exists and is recorded at the end of the year, so it is a stock and therefore a point-of-time quantity. Monthly income and annual output are flows measured over periods, while today’s debt is a stock. Hence, option C is correct.

Depreciation is a flow because it is measured over a period, usually a year. It reduces the value of the capital stock through physical wear, damage, or obsolescence. Investment and saving generally add to asset stocks, while income is simply a period flow. Thus, option C is correct.

Wealth is the total value of assets owned by a person or an economy at a particular point in time, so it is a stock variable. National income and investment are measured over a period and are therefore flows. Capital stock is also measured at a point in time. Thus, option D is incorrectly classified because wealth is a stock, not a flow.

Total bank deposits on a particular date represent an outstanding amount existing at one point in time; therefore, deposits are a stock. Interest income received during a year is accumulated over a specified period and is therefore a flow. The wording “on a date” signals stock, while “during the year” signals flow, making option A correct.

The classification depends on how the quantity is measured, not merely on the word used. Saving during a year is measured over a period and is therefore a flow. Accumulated saving or a deposit balance measured on a particular day is a stock. Hence option B correctly shows that context and time reference determine classification.

The phrase “in one quarter” identifies a definite period of three months. Sales accumulated during that quarter are measured over time and therefore represent a flow variable. Capital on 31 March, today’s cash balance, and population on a particular day are measured at points in time and are stocks. Therefore, option C is the only clear period indicator.

The expression “on 31 December” refers to one specific date, so it identifies a point-of-time measurement. Foreign exchange reserves on that date are a stock variable. Monthly expenditure, annual output, and weekly income are measured over periods and are flows. Thus, option D is the only answer that clearly indicates a point in time.

Total cost during the year is measured over the entire year, so it is a flow variable. Raw-material stock at the end of the year is the quantity existing at a particular date, so it is a stock variable. The words “during the year” and “at year end” provide the decisive clues. Hence option A is correct.

Rent income is earned over a period, and consumption expenditure is also recorded over a period such as a month or year. Both are therefore flow variables. Machine numbers, cash balances, population, capital, wealth, and outstanding debt are generally measured at a particular point in time and are stocks. Hence option C contains only flows.

Outstanding debt is the amount owed at a particular point in time, and the stock of machines is the quantity of productive assets existing at that point. Both are stocks. Annual income, monthly sales, weekly expenditure, production, investment, and exports are generally measured over periods and are flows. Therefore, option D is the only all-stock group.

Annual profit is the income earned after revenues and costs are considered over one complete year. Because it is measured for a period rather than at one instant, it is a flow variable. Capital stock and total assets on a specific date are stocks. Thus, the time expression “annual” makes option A correct.

Total assets on 1 April represent the value of resources owned by the company at one specified date. A quantity measured at a particular point in time is a stock variable. Capital expenditure and annual income are normally measured over a period and are flows. Therefore, the date-specific asset value is correctly identified by option B.

A flow variable records an amount generated, earned, spent, or produced over a specified period. The phrase “earned in one financial year” refers to income accumulated during that period, so it clearly describes a flow. The other statements refer to an amount existing or outstanding on a day or date, which indicates a stock.

A stock variable is measured at a specific point in time. The phrase “outstanding on a particular date” describes an amount existing at that date, such as debt or deposits, and therefore clearly indicates a stock. Monthly spending, annual earnings, and weekly sales are measured over periods and are flows. Hence option D is correct.

A stock variable represents an amount existing at a particular point in time, so the relevant date or time reference should be stated. Examples include cash on 31 March, debt at year end, or capital on 1 January. “Per year” and “during the year” describe flows measured over intervals. Thus, option B is correct.

A bank balance is the amount existing in an account at a particular point in time, so it is a stock. Monthly withdrawals are measured over one month, so they are a flow. The sequence in option A is therefore stock followed by flow. Options B, C, and D either reverse the order or begin with a flow.

Annual saving is measured over a year and is therefore a flow. Accumulated saving is the amount built up and held at a particular point in time, so it is a stock. Option B gives the required flow-to-stock sequence. Wealth and capital are stocks, while income, investment, and births are generally flows.

Investment is expenditure on or addition to capital goods during a period, so it is a flow. Capital is the stock of productive assets available at a particular point in time. Investment increases the capital stock, while depreciation reduces it. Therefore, option D correctly describes both the classifications and their economic relationship.

Household income for the year is earned over a twelve-month period, so it is a flow variable. Total wealth at the end of the year is the value of assets and liabilities measured at one particular date, so it is a stock variable. Thus, the correct sequence is flow and stock, given in option A.