Propability of x being less than y

I have a few pairs of data points (x,y)(less than 20).

How can I calculate the overall probability of x being less than y?

The differences of x and y range from -500 to 500.

I need the p-value(null hypothesis being that the difference is 0.) and the uncertainty boundaries for the difference x-y.

Answer 1

[Chunru]

In statistics toolbox, you can do the following:

x = randn(20, 2) * 200;
[h, pvalue, ci] = ttest2(x(:, 1), x(:, 2))