Why are you measuring it like that?

We measure, monitor and assess lots of things in our jobs. We frequently try hard not to think about poorly reproducible some things are – take breathlessness in children as discussed in a recent blog – and the whole literature is methodologically far weaker than that of intervention research. Sometimes we’re really like to assess something, but find it hard to work out exactly how to make that measurement: for example, what should we be measuring when looking at “time to antibiotics” in sepsis – door to ‘needle’ time? proportion less then one hour? first fever to antibiotic duration?

Sometimes it can help to take a completely different idea, to think about what elements might be important.

Say – “home field advantage” in competitive team sports

The idea of “home field advantage” is, as many people will know, that a home team is more likely to win than the away team. (Why is another question – not to be dealt with here.) Which team in a league has the greatest home field advantage – and how could you calculate that?

We could look at the proportion of games that are won at home. That will just tell us more about which teams are higher in the league.

We could look at the proportion of home wins compared to the proportion of away wins – that would give us an ‘internal control’ – and will get us a view of which teams outperform themselves in their own stadium. Although, this only tells us about if the home team got more points than the away team on each occasion. It’s not really the ‘magnitude’ of the advantage.

So we could look at the number of points scored at home, compared with away. Or perhaps points conceded, home vs. away, to tell us about the advantage when attacking and defending. Or maybe score difference, to capture the ‘A’ and the ‘D’ elements?

Which approach is correct? How would you judge which is the right way to measure it? Unpicking the elements involved might well give better clarity when next thinking how to make assessments at work.


(If you’d like to see how these things stack up in the area of rugby league, pop over to examine the UK SuperLeague stats examined in detail on this blog here.)

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