The American Institute of Stress, for instance, regards a score of 300 or more as an "80% chance of health breakdown within the next 2 years".
[5] Rahe carried out a study in 1970 testing the validity of the stress scale as a predictor of illness.
[7] The scale was also assessed against different populations within the United States (with African, Mexican and White American groups).
[8] The scale was also tested cross-culturally, comparing Japanese[9] and Malaysian[10] groups with American populations.
An article in Journal of Human Stress (Behavioral Medicine) noted several limitations, including: The sum of the life change units of the applicable events in the past year of an individual's life gives a rough estimate of how stress affects health.