From the paper:
An inevitable drawback of focusing on the within-person variation and not being able to isolate exogenous events is that we are unable to say anything concrete about the direction of causality.
...contrary to the authors' own statements that "Fostering the conditions where personality growth occurs – such as through positive schooling, communities, and parenting - may be a more effective way of improving national wellbeing than GDP growth."
This is a subtle but extremely common form of "burying the lead". Not directly committing the sin of confusing correlation and causation, but freely allowing correlation to "waggle its eyebrows and gesture furtively while mouthing 'look over there'" - letting readers draw the almost inevitable unwarranted conclusions.
...contrary to the authors' own statements that "Fostering the conditions where personality growth occurs – such as through positive schooling, communities, and parenting - may be a more effective way of improving national wellbeing than GDP growth."
This makes the study sound very politically motivated.
‘Is Personality Fixed? Personality Changes as Much as “Variable” Economic Factors and More Strongly Predicts Changes to Life Satisfaction,’ published in Social Indicators Research (doi: 10.1007/s11205-012-0006-z)
[...] small positive personality changes may lead to greater increases in happiness than earning more money, marrying, or gaining employment.
[...]
We found that our personalities can and do change over time – something that was considered improbable until now – and that these personality changes are strongly related to changes in our wellbeing.
[...]
Previous studies have shown that personality accounts for up to 35% of individual differences in life satisfaction, compared to just 4% for income, 4% for employment status and between 1% and 4% for marital status. However, because it was believed our personalities were fixed, policies to improve wellbeing have focused on these lower-impacting external factors.
[...]
“Fostering the conditions where personality growth occurs – such as through positive schooling, communities, and parenting - may be a more effective way of improving national wellbeing than GDP growth.”
[...]
Personality was measured using a well-validated personality questionnaire assessing five broad dimensions which cover the breadth of a person’s personality: openness-to-experiences, conscientiousness, extroversion, agreeableness and neuroticism. The researchers then looked at the extent to which personality changed and how these changes related to life satisfaction in comparison to external factors, such as changes to income, changes to employment and changes to marital status. They found that personality changes at least as much as these external factors and predicted about twice as much of changes to life satisfaction over the study period.
Link: manchester.ac.uk/aboutus/news/display/?id=8035