Purchasing Power for Numsita Coins and Banknotes - Chrome Extension

Hello all,

In addition to my project on a detailed Numista map I have also been collecting data on exchange rates between currencies.

I have built a chrome extension that adds additional lines to the infobox to give additional data relating to the items purchasing power.

I am not yet ready to release a test version as I do not feel it is that intuitive to understand the data in its current state. Some feedback on how you display this information would be appreciated.

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The first 2 lines use the inflation rate in the USA

100,000 Italian lire in 1983 -> US Dollars in 1983 -> US Dollars in 2024 $198.050

100,000 Italian lire in 1993 -> US Dollars in 1993 -> US Dollars in 2024 $131.781

The second 2 lines use the inflation rate in the UK

100,000 Italian lire in 1983 -> British Pounds in 1983 -> British Pounds in 2024 £150.700 -> US Dollars in 2024 $191.007

100,000 Italian lire in 1993 -> British Pounds in 1993 -> British Pounds in 2024 £86.213 -> US Dollars in 2024 $109.272

For items Pre 1700 I only have English/British inflation data and those Post 1700 I can use English and American Inflation Data

These 2 lines mean

8 Spanish Reales in 1556 -> grams of silver -> British Pounds in 1556 -> British Pounds in 2024 £55.472 -> US dollars in 2024 $70.309

8 Spanish Reales in 1598 -> grams of silver -> British Pounds in 1598 -> British Pounds in 2024 £33.727 -> US dollars in 2024 $42.747

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Moreover, for Silver and Gold coins post 1700 with a given weight and purity I can also give purchasing power as a percentage of face value. 

in the 1800s the Pound was on a gold standard and while their coins did have silver in them, it was not at the full value of silver. For example in 1887 it was 67% of face value i.e. in a 5 shilling piece there were only about 3.3 shillings of silver content.

I think I should display this information somewhere else but am not sure the best way to display it.

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Attempting to gather data for some countries has been very difficult for example the currencies of countries behind the iron curtain rely on official government rates, finding black market rates for every year of each currency has been difficult. I could display the offical government rate with a note perhaps, or just label them as not freely exchangable with US dollars.

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the program is quite versatile and can convert a few hundred currencies with the collected data. Essentially it converts the currency of the numista page into US dollars or British pounds of the time and then applies the consumer price index inflation rate to get to modern money.

https://www.minneapolisfed.org/about-us/monetary-policy/inflation-calculator

an example of how the process works would be 

1 Indian Rupee in 1912 → 0.32 US Dollars in 1912 → $9.937 US dollars in 2024

1 Indian Rupee in 1912 → 0.0667 British Pounds in 1912 → £6.923 British Pounds in 2024 → $8.775 US dollars in 2024

This is not a perfect process as 1 Rupee in India could buy many more goods than 0.32 US dollars in the USA due to differences in wages and purchasing power, but is an approximation.

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Anyway, if you have any good ideas of how I could display such purchasing power information intuitively let me know .

This is a really cool idea! I've been looking for something like this for a long time.

Here's my suggestion for how it should be presented, using the 100,000 Lire as an example:

Purchasing power in 1983, adjusted for inflation:

USD$198.050

GBP£150.700

Purchasing power in 1993, adjusted for inflation:

USD$131.781

GBP£86.213

The way it is currently presented is unclear if it is using 1983 or 2024 values. Perhaps you could also include a section for when the coin/banknote was demonetized, assuming a date has been included in the field.

I look forward to any updates!

Also, will this plugin be released for Firefox?

Some_Nerd

This is a really cool idea! I've been looking for something like this for a long time.

 

Here's my suggestion for how it should be presented, using the 100,000 Lire as an example:

 

Purchasing power in 1983, adjusted for inflation:

USD$198.050

GBP£150.700

 

Purchasing power in 1993, adjusted for inflation:

USD$131.781

GBP£86.213

 

The way it is currently presented is unclear if it is using 1983 or 2024 values. Perhaps you could also include a section for when the coin/banknote was demonetized, assuming a date has been included in the field.

 

I look forward to any updates!

I do not plan to release it for firefox at the moment.

that version you suggested is better but I also need a way to communicate that the USD value is adjusted for inflation in the USA and the Pound value for the UK

since 1983 and 1993 inflation has been different in the UK and the USA

to add this context it does make it less understandable overall, which isnt great.

Purchasing power in 1983, adjusted for inflation:

USD$198.050 in the USA

GBP£150.700 in the UK (USD $191.007)

Purchasing power in 1993, adjusted for inflation:

USD$131.781 in the USA

GBP£86.213 in the UK (USD $109.272)

An additional line for purchasing power when an item was demonitised is a good idea.

thanks