From what I can tell, dogs worked well in the laboratory, but it did not work well in the field. In the lab they usually had 1/5 or so positive samples, but in the field, it was a much lower positive rate depending upon cancer and the dog handler would not be able to give positive reinforcement immediately in the field, also different dogs have different success rates. https://www.livescience.com/61234-how-dogs-smell-cancer.html

very cool! I wonder if they could sprinkle in some fake examples for the dogs so that they could give positive reinforcement more often.

I saw some studies recently stating that humans' sense of smell is actually as good as dogs.

The baseline is not humans smelling breath, it's humans looking at a graph.

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