When is it inappropriate to use "multiple"? The sentence in question is "The sample procedure may be repeated multiple times." It means the test being run will occur until the participants get it right. The testing is scheduled to take a month.
'Multiple' = more than once.
'Numerous' = many

Choose the word that applies to your context.
AnonymousIt means the test being run will occur until the participants get it right.
In this situation I would use 'multiple'. You're saying that the participants do not have to get the test right the first time. They may, however, get it right the first time or the second time, so they don't necessarily repeat it numerous times.

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Multiple describes a mathematical function of bringing several, usually different, parts together:

mul·ti·ple [muhl-tuh-puhl] adjective
  1. consisting of, having, or involving several or many individuals, parts, elements, relations, etc.; manifold.
Therefore, you don’t have “multiple” phone calls and plaintiffs don’t engage in a “multiple” of acts (defendants don’t either).

What you mean to say, when describing many things, is “numerous:”

nu·mer·ous [noo-mer-uhs, nyoo-] adjective
  1. very many; being or existing in great quantity: numerous visits; numerous fish.
If numerous doesn’t sound erudite enough for someone as smart as you, perhaps you would prefer “several:”

sev·er·al [sev-er-uhl, sev-ruhl] adjective
  1. being more than two but fewer than many in number or kind: several ways of doing it.
 CalifJim's reply was promoted to an answer.
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