From the course: Excel: Statistical Process Control
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Calculate the mean and standard deviation of proportion data - Microsoft Excel Tutorial
From the course: Excel: Statistical Process Control
Calculate the mean and standard deviation of proportion data
- [Instructor] When you are analyzing proportional data, that is, you're looking at the proportion of defective units within a sample, you don't use the average and STDEV.S functions like you would for normally distributed data. Instead, you need to calculate the mean of the proportions. So, what you do is you find the proportion of defects in each batch. That is, the proportion of defective units. And then you take the average of those proportions, which is called p-bar. So, p with a horizontal bar on top of it. To calculate the standard deviation, you use a different formula. And this takes a little bit of work to enter, but I'll show you how to do it. You take the square root, p-bar, which is the average of proportions of defective units, and multiply that by one minus p-bar. And you divide that quantity by n, and take the square root of the entire quantity. So again, once you know the average of the proportions, called p-bar, you can use this function to calculate. Now I'll switch…
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