Skewness overview and how to calculate Skewness

 The Complete Guide to Skewness and How It Affects Your Data

What is Skewness and How Does it Affect Your Data?

Skewness is a statistical measure that describes how a sample or distribution is asymmetrical. A data set with a higher number of low values than high values will be negatively skewed, and a data set with a higher number of high values than low values will be positively skewed. The data set’s overall shape, as shown in the graph below, is referred to as its ‘distribution.


’ The ‘middle’ of that distribution – the number that sits at the 50th percentile mark – tells us the data set's average value. The average value of a positively skewed data set will be above the 50th percentile mark, while the average of a negatively skewed dataset will be below it.




Skewness is a measure of asymmetry in the distribution of a data set. It is the third moment about the mean. The skewness coefficient can be used to show how distribution is "peaked".

The skewness coefficient indicates the degree to which data points cluster around the mean. A positive skew indicates that most of the data points are on one side of the mean and negative skew indicates that most of them are on the other side.

Calculating Skewness in Statistics

 How to Measure Data Set Skewness? If a data set is positively skewed, there will be a long tail stretching out to the right of the graph. If you’re using a graph to measure a data set’s skewness, you can draw a line from the left-hand side of the graph to the 50th percentile mark. The distance between the graph line and the 50th percentile mark is the data set’s skewness. If the data set has a positive skew, the line will be further away from the 50th percentile mark than the line for a negatively skewed data set. 

Why Is Understanding Skewness Important? Understanding the degree of a data set’s skewness can help determine whether a data set is suitable for a given type of analysis. For example, a positively skewed data set that is being used as a control group in an experiment will skew the results in favor of the treatment group. This means that the control group might not be suitable for the experiment, as it could have different characteristics that could skew the results. A negatively skewed data set can also skew results but in a different way. If the values in the control group are much lower than those in the treatment group, this can skew the results in favor of the control group.

How Skewed Data can Impact Businesses

Skewed data can impact businesses in several ways, but the most significant one is that it can lead to wrong decision-making. For example, if a company is using biased data to make decisions about its marketing campaign, then the company might end up targeting the wrong audience. This will cause a waste of resources and the company won’t be able to achieve its business objectives.

Skewed data can also lead to bad customer service. In this case, if a business has inaccurate customer records with incorrect information about their customer’s preferences and buying habits, then they will have trouble providing them with what they want and when they want it.

Skew-Tails and the Role of Skewed Distributions in Statistics

Skew-tails are statistical distributions that have a disproportionate number of values on one side of the distribution. This often results in a long tail on one side and a short tail on the other.

The skew-tail is important because it can be used to detect potential outliers in data sets.

Statistical Tools That Help Detect Skewness

Box Plot - A box plot is a visual representation of data that can be used to identify outliers, detect skewness, and more. The data set’s skewness will be shown in either the middle or the end of the box plot. - Standard Deviation - A data set’s standard deviation is a measure of its variability. It’s calculated by taking the deviation between each data point and the mean, squaring each of those figures, adding them together, and then taking the square root of that total. Higher variability leads to higher standard deviation, and lower variability means lower standard deviation. A higher standard deviation is a sign of a data set with a high degree of skewness. - Histogram - A histogram is a visual representation of data that shows how many data points fall within certain ranges. A histogram can be used to identify skew, outliers, and other issues. - Box and Whisker Plot -

Conclusion: The Importance of Understanding the Concept of Skewness in Statistics

When we think of data sets, it’s natural to imagine all the data fitting neatly into a nice, symmetrical bell curve. After all, that’s what we see when we look at most graphs. However, as is often the case in real-world scenarios, things aren’t quite so neat and tidy. Statistics help us make sense of messy data; they allow us to measure exactly how messy the data set is. The measure of this ‘messiness’ is called skewness, and it describes whether a data set has a tail extending towards the left or right side of its graph. If a data set is positively skewed, there will be a tail extending towards the right (i.e., there are more high numbers than low numbers). A negatively skewed dataset will have more low values than high ones – its tail will extend to the left.

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