Tuesday, March 7, 2023
HomeHealth InsuranceWhat's a Tukey outlier? – Healthcare Economist

What’s a Tukey outlier? – Healthcare Economist

Beforehand, CMS applied a Tukey outlier deletion technique when calculating Medicare Benefit (MA) and Medicare Half D Prescription Drug Plans (PDP) star ranking. A Ultimate Rule applied in 2022, nevertheless, eliminated using Tukey outlier deletion from high quality measures. Based mostly on 2020 historic knowledge, 17% of MA plans would have decrease star rankings as in comparison with just one% would have greater star rankings after eradicating the Tukey outlier deletion. This begs the query, what’s a Tukey Outlier.

Tukey Outlier Definitions.

Tukey outliers are knowledge factors that lie outdoors the next vary;

  • {Q1 – ok(IQR), Q3+ok(IQR)}

Right here Q1 and Q3 are the primary and third quartiles of the information respectively and IQR is the interquartile vary (i.e., the distinction between the third and first quartile). The time period ok is a multiplier, which describes how delicate you’ll need to be to outliers. John Tukey proposed that ok = 1.5 signifies an “outlier”, and ok = 3 signifies knowledge that’s “far out”.

How possible are you to determine an outlier with the Tukey technique?

The reply to this query relies on (i) how broad your Tukey vary is (i.e., the worth of ok) and (ii) the form of your distribution. Andrey Akinshin created simulations to reply this query for Regular, Gumbel and exponential distributions. The outcomes are beneath. As you’ll be able to see beneath, non-normal distributions–particularly exponential–are more likely to have an outlier noticed utilizing the Tukey technique.


Like all outliers, identification is vital however what to do with them relies on context. If these are knowledge errors or pure anomalous conditions, one could need to delete them. Alternatively, if these are simply outlier values that occur from time-to-time, one ought to go away them within the knowledge and simply attempt to higher perceive if there’s a knowledge producing course of which differs from the common one which may generate these values. Both method, the Tukey technique is a useful, easy method for figuring out outliers, nevertheless it doesn’t inform you what to do with them as soon as they’re recognized.



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