Browse the glossary:

• N-of-1 trial see single participant trial (single case design)
  — A study in which different treatments are allocated at random to be taken at different times by one person; … (read more)
• natural course of health problems (natural history*, natural progression*)
  — The course of a health condition (worsening or improving) without treatment; … (read more)
• negative predictive value (NPV)
  — The proportion of people with a negative test result who do not have the disease or target condition of interest; … (read more)
• nocebo effect
  — Undesirable effect that is or could be caused by an inactive treatment, presumed to act psychologically through suggestion; … (read more)
• non-random allocation (quasi-random allocation)
  — Methods of allocating study participants to treatment comparison groups that are not random, but are intended to produce similar groups.; … (read more)
• non-randomized study (non-experimental study, observational study,)
  — A category of studies that does not use random allocation to assign participants to treatment comparison groups; … (read more)
• number needed to harm (NNH, NNTH)
  — The number of people who would need to be treated over a specific period of time before one bad outcome of the treatment will occur; … (read more)
• number needed to screen (NNS, NNTS)
  — The number of people who would need to be screened over a specific period of time before one good outcome of the screening will occur; … (read more)
• number needed to treat (NNT, NNTT)
  — The number of people who would need to be treated over a specific period of time before one good outcome of the treatment will occur; … (read more)