The CPI is most often used to make comparisons partly because it is the series with which people are most familiar. This series tries to compare the cost of things the average household buys such as food, housing, transportation, medical services, etc. For earlier years, it is the most useful series for comparing the cost of consumer goods and services. It can be interpreted as how much money you would need today to buy an item in the year in question if its price had changed the same percentage as the average price change.

The GDP Deflator is similar to the CPI in that it is a measure of average prices. The "bundle" of goods and services here includes all things produced in the economy, not just consumer goods and services that are reflected in the CPI.

Average Earnings is a good way to determine the relative cost of something in terms of the amount of work done by the average worker that it would take to produce, or the relative time spent in work by that worker in order to earn its cost. "Earnings" here represent an estimate of the total monetary value of the compensation an average worker in full time employment would get per week. There is also an index based on the national minimum wage.

The GDP per capita is an index of the economy's average output per person and is closely correlated with the average income. It can be useful in comparing different incomes over time.

The GDP is the market value of all goods and services produced in a year. Comparing an expenditure using this measure tells you how much money in the comparable year would be the same percent of all output.

Real Price is measured as the relative cost of a (fixed over time) bundle of goods and services such as food, shelter, clothing, etc., that an average household would buy. In theory the size of this bundle does not change over time, but in practice adjustments are made to its composition. This measure uses the CPI.

Labour Value is measured as the multiple of the average wage that a worker would need to use to buy the commodity. This measure uses one of the wage indexes.

Income Value is measured as the multiple of average income that would be needed to buy a commodity. This measure uses the index of GDP per capita.

Economic Share is the worth of a commodity in a particular time period divided by GDP; it is its share of total output. This is helpful in measuring the relative value of aggregate consumption items such as all the cars made in a year.

Real Wage or Real Wealth measures the purchasing power of an income or wealth by its relative ability to buy a (fixed over time) bundle of goods and services such as food, shelter, clothing, etc. This bundle does (in theory) not change over time. This measure uses the CPI.

Relative Labour Earnings measures an amount of income or wealth relative to the wage of the average worker. This measure uses one of the wage indexes.

Relative Income measures an amount of income or wealth relative to per capita GDP. When compared to other incomes or wealth, it shows the economic status or relative "prestige value" the owners of this income or wealth because of their rank in the income distribution. This measure uses GDP per capita.

Relative Output measures the amount of income or wealth relative to the total output of the economy. When compared to other incomes or wealth, it shows the relative "influence" of the owner of this income or wealth has in controlling the composition or total-amount of production in the economy. This measure uses the share of GDP.

Real Cost of a project is measured by comparing its cost to the cost index of all output in the economy. This measure uses the GDP Deflator.

Labor Cost of a project is measured as a multiple of the average wage of the workers that might be used to build the project. This measure uses one of the wage indexes.

Economy Cost of a project is measured as the cost of the project as a percent of the output of the economy. This measure indicates the opportunity cost in terms of the total output of the economy. It can be interpreted as the importance of the item to society as a whole. This measure uses the share of GDP.

In 1932, the year it opened, the fare on the Sydney Harbour Bridge was 6 pence for a car (half that for horse and rider.) In 2018, the relative real price of that 6 pence is $2.06 and the labour value is almost $9.52. The income value is $16.66. The current toll on the bridge during peak time is $4.00, so the commute is a bit more expensive in in terms of goods, but lots cheaper in relative earnings.

The alluvial gold rushes from 1851 had a major impact on the Australian colonies. In the short term there was massive disruption, with food shortages and severe inflation as workers left their jobs to go to the gold fields but, in the longer term the gold rushes transformed Australia's growth possibilities. The total value of gold produced - mainly in Victoria - in the peak alluvial phase from 1851 to 1860 was £17.7 million. How can we best measure the relative value of this amount?

Although gold is a commodity, the gold rushes were an economic event which lasted at least ten years and its impact is best measured relative to the economy as a whole. On MeasuringWorth, this means thinking of the gold rushes as a project. There are two appropriate choices for evaluating the relative worth of such a project of £17.7 million in 1851. The first is to use the GDP deflator, a price index for all goods and services (real cost), which gives a value of $4.52 billion in 2018 prices. The second is to measure the gold rushes relative to GDP (economy cost), which gives a value of $1.96 billion. This measure is often depicted as the opportunity cost of an event or project, but the gold rushes expanded the opportunities by attracting new migrants and capital.

The Overland telegraph is a 3,200 kilometer telegraph line through the heart of Australia. Traversing the continent in North-South direction the cables were strung through the unexplored and seemingly impenetrable Outback linking Adelaide, and the existing Australian telegraph networks, with an undersea cable landing at Port Darwin. This technological feat cut the time it took to send messages from Australia to Europe from weeks to almost immediate transmission.

The colony of South Australia approved in 1870 a budget of £120,000, pre-empting other states and successfully routing the line through its territory. The initial amount however severely underestimated the required expenses as the capital costs ended up at a staggering £479,174 18s. 3d after completion of the line in 1872.

The relative real cost of that 1870 budget in 2018 is $21.8 million, a sizeable but not overwhelming amount for an infrastructure project. As labour was a substantial part of the construction costs the 2018 labour cost of the budget would be $139 million in relative wages at average weekly earnings. In terms of share of GDP (economy cost) represents a relative value of $2.12 billion in 2018, a rather substantial undertaking for a (white colonial) population of barely 190,000. It's also very similar to the $1.8 billion investment of Australia's National Broadband Network Satellite program launched in 2015, which provides high-speed internet to about 400,000 Australians living in remote areas. The final bill in 1872 of £479,174 18s. 3d in comparison represents an economy cost of $7.78 billion in 2018, which reinforces the substantial investment in connecting Australia to the rest of the world this telegraph line was. Australia currently invests $56 billion to bring high-speed internet to most of the country, with the cost share for the state of South Australia probably above $4 billion. Connecting Australia to the larger world was a very costly undertaking in 1872 and it is still today.

Source: Frank Clune "Overland telegraph: the story of a great Australian achievement and the link between Adelaide and Port Darwin" Angus and Robertson, Sydney, 1955

An important moment in Australia's industrial development was the first all-Australian mass produced car. The Holden 48-215, commonly known as the "FX", was unveiled at the end of 1948 with a price tag of £733. That sticker price clearly increased from £733 in 1949, so looking at it in 2018 terms we find a real price of $39,400, which is not dramatically different from the prices of current popular full sized sedan car models. In terms of labour value the price tag represents $123,000 in 2018, using average weekly earnings, which indicates that the average worker had to work substantially longer than their modern counterparts to be able to afford such a car.

Attracting qualified medical personal to remote locations seems to have been a problem now and then. In 1870 the mining community of Yankalilla on the Fleurieu Peninsula advertised for a new surgeon as their current one had decided to move on to even more remote areas. The ad stated that the annual income of the previous resident had never fallen below £260 a year. What does that income buy today? Using the CPI (real wage) to bring it to 2018 values results in $30,920, hardly an enticing salary. However, compared to average weekly earnings the relative income represents $301,800, a number quite in line with today's salaries for specialized medical doctors.

South Australian Advertiser, 04.01.1870

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