Test In Groups
Test in overlapping groups until every pair has been split once; the culprit sits in every failing group and no passing one.
Formerly Deconvolve
Pooled blood tests, 1943: test the pool; open it only if it fails.
Seen in Mordecai Meirowitz, Mastermind, 1970
Try it on your work
Take eight parts of the thing you're working on whose contribution you cannot tell apart. Test them in overlapping groups of four, each part in two groups, until every pair of parts has been separated at least once. Stop when every group has been tried. A part present in every failing group and no passing one is the culprit.
List eight words you suspect are doing damage to your project's description. Write four versions, each omitting a different overlapping half. Stop at four. Read which versions improved; the word present in every worse version and absent from every better one is the one to cut.
Your process has six steps and something is wrong. Run it three times, each time skipping two overlapping steps, so every step is skipped once and present twice. Stop at three runs. Whichever step's absence coincided with the improvement is the step to remove.
How it has been used
Combinatorial pooled testing can identify a positive sample without testing every sample separately. Each sample is placed in a distinctive combination of pools; when several pools test positive, their overlap points to the contributor. During large-scale disease screening, this logic reduced the number of laboratory tests while still allowing individual samples to be identified.
Where it leads
Grouped under Let me find out what holds up