 ለምሳሌ, ማጨስ ካንሰር እንደሚያስከትል ሁሉም ሰው ይቀበላል, ምንም እንኳ ሰዎችን ወደ ማጨስ የሚያስገድድ ያልተቃለለ ቁጥጥር ሙከራ ቢደረግም.
For example, we know that smoking causes cancer even though no one ever ran a randomized experiment to measure the effect of smoking.