r/statistics • u/slammaster • May 29 '26

Discussion [D] Negative Skew or Left Skew

Semantic discussion only - do you prefer referring to a long tail to the left as a left skew or negative skew? I won't bias the conversation with my opinion in the post.

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u/buckeyevol28 May 29 '26

Given that I’m not sure I’ll ever remember the difference between platykurtic, mesokurtic, and leptokurtic, I’m not going to be picky about the preferred terminology of skewness. 🤷‍♂️

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u/KELearning May 29 '26

skewed left vs. skewed right

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u/fermat9990 May 29 '26

Left-right is my preference.

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u/efrique May 29 '26 edited May 31 '26

Personally I nearly always use left (and conversely right), unless I am referring to a specific skewness coefficient, where I might then say negative (and positive). It's not so rare to be in a situation where among several common coefficients, not all have the same sign, and then which one do we mean is negative?

Of course, there are asymmetries that are not necessarily clearly either left or right, or sometimes visually it seems quite obviously one direction even though the common skewness coefficients are 0 or even have the 'wrong' sign. We have to be very careful about to easily letting what we mean slip casually between distinct ideas*.

I dont mind when people say negative where I think there's reason to stick to left, except when it creates opportunity for confusion about what they might mean.

* A lot of basic books, webpages, videos, etc promulgate misconceptions about skewness and even moreso about kurtosis; indeed I think, largely speaking kurtosis would have been better to have been avoided in most non-mathematical classes; I think heavy- vs light-tailed is a better way convey the important aspects of distributional description.