For a company the size of Google, 4 barges probably DOES count as a tiny initial test. I suppose 4 simultaneously has some advantage over 1 at a time because it allows you to do A/B/C/D testing.
Anyone else would have a striped + mirrored RAIB. But I suppose at Google's scale, they need geographically distributed barges to cover for a failure at one port.
You'd want aabc, at least. You need to test your treatment against itself as a control. If you see significance between control A and treatment A, you have noise.
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For a company the size of Google, 4 barges probably DOES count as a tiny initial test. I suppose 4 simultaneously has some advantage over 1 at a time because it allows you to do A/B/C/D testing.
Anyone else would have a striped + mirrored RAIB. But I suppose at Google's scale, they need geographically distributed barges to cover for a failure at one port.
You'd want aabc, at least. You need to test your treatment against itself as a control. If you see significance between control A and treatment A, you have noise.