This article describes seven reasons why people may erroneously conclude that an ineffective therapy works. The disease may have run its natural course. Many diseases are self-limiting. If the condition is not chronic or fatal, the body's own recuperative processes usually restore the sufferer to health. Without detailed records of successes and failures for a large enough number of patients with the same complaint, someone cannot legitimately claim to have exceeded the published norms for unaided recovery.
Many diseases are cyclical.
Naturally, sufferers tend to seek therapy during the downturn of any given cycle. In this way, a bogus treatment will have repeated opportunities to coincide with upturns that would have happened anyway. The placebo effect may be responsible. Through suggestion, belief, expectancy, cognitive reinterpretation, and diversion of attention, patients given biologically useless treatments often experience measurable relief. People who hedge their bets credit the wrong thing.