What are the four criteria that should be met in the use of N of 1 Randomized Clinical Trials?

What will be an ideal response?

(a) The patient's problem must be chronic but stable so the effect of treatment over time can be seen.
(b) The treatment (usually a drug) should have a rapid effect and rapid cessation of effect when it is withdrawn so lingering effects don't persist in a placebo period.
(c) There have to be clear and objective goals that can be measured reliably. Different observers could draw different conclusions if criteria are too subjective
(d) The researcher needs to have a strategy for the analysis and interpretation of outcomes, again to avoid inappropriate conclusions.