This article will show you how to Prove Process Improvement with Paired T Test.

In you process improvement projects, you will almost – no, inevitably – make process changes. At times, you will be challenged on whether the process change made any difference at all. Sound familiar?

To statistically show whether there was a difference in the Before/After of a process change, the statistical test that can help is what’s called the Paired-T Test.

## What’s the Paired T-Test?

A paired t-test compares two samples in cases where each value in one sample has a natural partner in the other.

## What does a Paired T-Test Measure?

A paired t-test looks at the difference between paired values in two samples, takes into account the variation of values within each sample, and produces a single number known as a t-value.

You can find out how likely it is that two samples from the same population (i.e where there should be no difference) would produce a t-value as big, or bigger, than yours. This value is called a p-value. So, a t-test measures how different two samples are (the t-value) and tells you how likely it is that such a difference would appear in two samples from the same population (the p-value).

Some examples where a paired t-test makes sense to use are:

- Comparing the weight of people dieting after a controlled diet
- Comparing the performance of order pickers before and after a change to the picking process or pick path
- Comparing the level of defects before and after a process change

You get the point.

So, enjoy the free excel calculator and be sure to use it in your projects. And, if the calculator doesn’t do what you need it to do, then feel free to improve upon it.

Check out the video I made below of what the paired t-test calculator looks like and what it can do for you.

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