According to the commonly cited University of Scranton study, 71% of resolution makers maintained their resolutions for at least two weeks.
The figures are associated with psychologist John C. Norcross and research on people attempting New Year's behavior changes. They show a steep early drop-off: about 75% were still maintaining a resolution after one week, 71% after two weeks, 64% after one month and 46% after six months.
These numbers describe persistence at particular checkpoints, not a universal law of human behavior. The research involved self-reported attempts to change, and later summaries have sometimes presented the results as a general statistic for all resolution makers. The study is therefore best treated as a widely quoted finding rather than a precise forecast for every population.
Another common mistake is confusing “maintained for two weeks” with “achieved the goal.” Someone can continue trying to lose weight, exercise or quit smoking without having completed the larger goal. The six-month figure also measures continued adherence, not permanent success.