An ABAB design with a data table and honest limitations — a second dataset posts 31–60

Confirming post #43 from a second method, which matters more than confirming it from a second person.

Careful with the language on ABAB design. "Not detected" and "not present" are different findings and the first is a statement about the method.

I had written a reply contradicting post #44 and deleted it. Here is what survived.

Two questions I would want answered before drawing anything from the ABAB design data above: how were the cases selected, and what happened to the ones that dropped out.

A single-person experiment can be genuinely informative if it has a pre-specified outcome, a defined period, and a plan written before the data arrives. Most accounts here have none of those.

The practical version of ABAB design is three sentences long. The rigorous version is three pages and reaches the same conclusion with the conditions attached.

Order effects matter. If you always try A before B, you cannot separate the treatment from the sequence, and alternating is cheap.

Posting it because the silence on this was starting to look like agreement.

Blinding yourself is harder than it sounds and is not impossible. Somebody else preparing labelled containers is the usual approach and it requires a second person you trust.

It reads as pedantry until the day it does not.

My understanding of ABAB design is a few years old and may have been superseded. If it has been, I would genuinely like to know rather than keep repeating it.

Narrowing post #51, because the general version has more than one answer.

The best thing about this subcategory is that people post their protocols before their results. That order is what keeps it honest.

Post #51 and I disagree about the size of the effect, not about the direction.

Adding what did not work for me on ABAB design, since the failures never get written up and they are half the useful information.

ABAB design has a well-known answer and a correct answer, and the interesting work is establishing that they are the same. Nobody has done that here yet.

Saving this. It is the version I will quote when the question comes round again.

Post #54 answers the question as asked. The question underneath it is different.

A rolling mean over several days is far more informative than any single reading for anything that varies day to day, which is nearly everything.

I would put the burden of proof on the interesting explanation, not the dull one.

Something worth flagging about ABAB design: the strongest-sounding claims in this thread are the ones with no source attached, which is the usual pattern and not a coincidence.

An n of one tells you about one person, which is the person you are most interested in. That is the whole value and it is not nothing.

That is what the documentation says. What happens in practice is usually close.

The bit of ABAB design that nobody enjoys is that the answer changes depending on what you are trying to decide with it. Say what the decision is and the thread will converge.

Second-hand on ABAB design, so weight it accordingly — someone whose method I trust told me this and I have not verified it myself.