Finding Outliers in Excel using the Mean and Standard DeviationĪnother simple way of detecting outliers is by using the Standard deviation of the data distribution. You can use the formula of Step 7 as the condition for formatting the cells. Note: Alternatively you can also use conditional formatting to highlight the outliers in your data. You should now see a TRUE value next to all the outliers in your data. Consider the following list of data values:
#Find x given mean and standard deviation excel how to
Let us take an example to see how to apply the above method in Excel.
Find the points that are smaller than the lower bound or larger than the upper bound. 
Calculate Upper bound by multiplying IQR by 1.5 and adding it to the Q3. Calculate Lower bound by multiplying IQR by 1.5 and subtracting it from Q1. Calculate IQR by subtracting Q1 from Q3. Calculate Q1 and Q3 using the QUARTILE function for your data. In a nutshell, the sequence of calculations to find outliers in your data are: Similarly, we can calculate the upper bound limit by multiplying the IQR value by 1.5 and then adding it to the Q3 value: Upper Bound = Q3+(1.5 * IQR) We can calculate the lower bound limit by multiplying the IQR value by 1.5 and then subtracting it from the Q1 value: Lower Bound = Q1-(1.5 * IQR) Here’s how you can calculate the lower and upper bound values: So any value that is smaller than the lower bound or larger than the upper bound are the outliers. Once you have the Q1, Q3 and IQR values, you can use these three to calculate the smallest and largest values of the acceptable data range (also known as the Lower bound and Upper bound respectively). Similarly, if you want to calculate the third quartile, you need to specify the quart parameter as 3. If you want to calculate the first quartile, you need to specify the quart parameter as 1. quart is a number that indicates which quartile you want to calculate. array is the range of cells containing your data. The syntax for the function is as follows: QUARTILE.INC( array, quart) These quartile values can easily be calculated using the QUARTILE.INC function in Excel. Similarly, the third quartile (Q3) consists of the values that are just above the median (values that are between 50% to 75% of the data). 
The first quartile (Q1) consists of the lowest 25% of the data. In order to calculate the IQR, we need to know the first and third quartiles of the data, because the formula for calculating IQR is: IQR = Q3 - Q1Ī quartile consists of a quarter of the values in the data, when the data is sorted from the smallest to largest values. Let us first understand how the Inter-Quartile Range is calculated. So any value that is away from this cluster of data is most probably an outlier. The Inter-Quartile Range (IQR) is a measure of where the beginning and end of the bulk of your data lie.
Finding Outliers in Excel using the Z-Scoreįinding Outliers in Excel using the Inter-Quartile Range. 
Finding Outliers in Excel using the Mean and Standard Deviation. Finding Outliers in Excel using the Inter-Quartile Range.
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