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Context changes everything

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Case study

30 January 2020

Context can even change what a measurement means.

You've probably heard the story about how NASA lost a Mars probe. One of their suppliers was working in inches while the other suppliers were working in centimetres. They were using the right numbers, but they had different ideas of what those numbers meant.

But what if you were dealing with a situation where one person's centimetre was different to someone else's? Context changes everything.

This is the situation people have been dealing with over the tough summer, with bushfires causing Australians to suddenly pay attention to the Air Quality Index or AQI.

Problem is, there isn't just one AQI.

In Australia, the National Environment Protection Council (NEPC) determines the AQI. The NEPC is a cross-jurisdictional council of State, Territory and Federal Ministers who take advice from scientists and decide what clean air is (as well as other environmental standards).

For air, the standard measures are:

While Australians live in an Australian regulatory environment, governed by the NEPC, we live in a global economic environment. This means a lot of products, such as air filters, use different versions of the AQI.

These economics can also affect information sources. Because the US and China buy more air filters, more websites and apps use US and Chinese versions of the AQI. Until this past summer, Australians haven't necessarily been super concerned about air quality, so websites haven't worried about the Australian standard.

The Australian standard is usually stricter about what is unhealthy for people to breath. This is especially true with the sorts of particles we've had blowing in. 

Ok, but apart from explaining the different numbers you might see in your air quality app, what does this mean for you?

Mainly it’s remembering that context will make a big difference to the solution. Generally speaking, you can't copy and paste something and have it work straight away.

And there is an argument here in favour of international standards: a kilogram is a kilogram is a kilogram is a kilogram. Even more so now that it's based off calculations from universal constants, not measuring a decaying hunk of metal in France.

But… even with an international standard, context is still super important. Take the example of temperature. We all measure it in degrees Celsius (except our American friends and, like, three other countries - c'mon guys).

As our friends at the Bureau of Meteorology (BOM) point out, the official temperature is measured in white boxes, with the thermometers protected from the sun and wind.

But if you're going to be in full sunlight on a humid day, or up the top of a mountain with gale-force winds, the temperature you experience is going to be very different.

This is why BOM now lists a 'feels like' temperature that takes into account the humidity, wind speed etc.

So be like BOM. Remember context. Someone else's experience of a measurement might not be the same as yours.

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