# OECD Gender wage gap data analysis 2 - Statistical Inference with Infer package, mean difference, calculation p-value with simulation based method

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This post is following of the above post.

In the previous post I see mean of EMPLOYEE is 17.9 and mean of SELFEMPLOYED is 30.6.

Let's see whether the difference is statistically significant or not.

Before doing statistical inference, let's do visualization.

I see SELFEMPLOYED Value is wider spreaded than EMPLOYEE Value.

Now, let's start statistial inference.
I will follow the methodology of B Inference Examples | Statistical Inference via Data Science (moderndive.com)

I calculate observed statistics, difference of mean, SELEMPLOYED mean - EMPLOYEE mean.

So, 12.7 is the difference.

Then, I make null distribution of the difference.

Now, I can do visualization for null distribution using visualize() function.

I see the center of stat is 0.

Let's see p-value on the above histogram.

I see the red vertical line is far away from the null distribution, it means p-value is very very small.

Let's calculate p-value.

Calculate p-value is 0. So I can say the difference of mean between SELFEMPLOYED and EMPLOYEE is statistically significant.

That's it thank you!
Thank you Statistical Inference via Data Science (moderndive.com) !

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