Let it run a bunch of times and visualize your data.

Here's an example of a shuffle from Coding Horror, you can see that the algorithm is OK or not:

Let it run a bunch of times and visualize your data.

Here's an example of a shuffle from Coding Horror, you can see that the algorithm is OK or not:

It's easy to see that every possible item is returned at least once (the boundaries are OK) and that the distribution is OK.