[2026 update] Reading a supplementary appendix and finding the interesting part posts 31–45

On Reading a supplementary appendix, the part that usually goes wrong is that the question is asked as though it has one answer. It has a range, and the width of the range is the interesting bit.

If you can post the two or three numbers you are working from, several people here will check the arithmetic rather than argue about the conclusion.

This follows post #29 rather than contradicting it.

I would rather this thread reach "we do not know" about Reading a supplementary appendix than reach a confident answer that nobody can support when asked.

Risk of bias: structured appraisal of internal validity. Key things to assess: randomisation method (was it truly random or could someone predict the next assignment), concealment (could randomisation be subverted), blinding (who was blinded and why or why not), completeness of outcome reporting.

Adding the caveat now so it does not have to be extracted later.

This is the sort of exchange that makes the archive worth searching.

Composite endpoints should be read component by component. A composite driven entirely by its softest component is a different finding from one where the components move together.

That is where I would start, not where I would stop.

Where the Reading a supplementary appendix reasoning breaks down for me is the step from the group result to the individual case. That step is almost never argued for.

Coming back to post #33, because the follow-up matters more than the original answer.

The most useful thing anyone has posted about Reading a supplementary appendix in this category was a table of what had been measured and by whom. That is what I would want again.

Absolute and relative effects answer different questions. Write down the event rate in each arm and the difference between them; everything quotable is derived from those two numbers.

Reporting the observation and leaving the explanation open deliberately.

I disagree with the framing of Reading a supplementary appendix above, and I think it is a substantive disagreement rather than a terminological one. Setting out why, so it can be checked.

The reasoning depends on an assumption that is doing a lot of work and is never stated. If the assumption holds, the conclusion follows. I do not think it holds generally.

Risk of bias: structured appraisal of internal validity. Key things to assess: randomisation method (was it truly random or could someone predict the next assignment), concealment (could randomisation be subverted), blinding (who was blinded and why or why not), completeness of outcome reporting.

Someone should write this up properly, and it should probably not be me.

Worth separating Reading a supplementary appendix as a question about the compound from Reading a supplementary appendix as a question about the documentation. They get answered by different people and only one of them is answerable here.

This is the first time the answer has come with its own limits attached. Appreciated.

The question underneath Reading a supplementary appendix is usually "how would I tell?" rather than "what is true?", and that one has a method attached to it.

Write down what you would expect to see under each hypothesis before you collect anything. If they predict the same observation, collecting it will not help.

Everything in post #40 holds. The case it does not cover is the one I have.

Absolute numbers, not just relative: a 30% relative reduction tells you the ratio but not the practical magnitude. The event rate in each arm and the difference between them tells you how many people benefit.

Take the reasoning and check the arithmetic; I do not always get it right.