Levels of measurement - what you can and can't do arithmetically

# 2. Nominal scales of measurement

At the nominal level the numbers assigned to an attribute are simply representations so they can’t be added or subtracted or subjected to any arithmetic process. But the numbers in each category can be counted.

In the spreadsheet shown, a team of footballers was asked whether they were left or right footed. Left footed players are entered onto the spreadsheet as 1 and right footed players as 2. How many left footed and right footed players are there in this team?

Yes that's right there are 2 left and 9 right footed. So you can see it’s perfectly valid to count the numbers (or frequency) in each category, but to average the 1s and 2s would be nonsense.

Similarly adding up all the numbers on footballers shirts is possible - it comes to 66 - but this figure doesn't mean anything!

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