Can you measure happiness – especially as a function of age?

The European Centre for Social Welfare Policy and Research in Vienna, Austria, has developed a paper that looks into the relationship of ageing and happiness.

It seems that ageing per se does not result in a decline in happiness. But happiness is closely affected by changing preferences (by the decreasing importance of work, the increasing importance of religion, and the declining disutility of being single), and partly by changing circumstances. While changing preferences seem to increase well-being, changing circumstances seem to decrease it. Old days thus are happy above all due to changing priorities in life.

It seems logical to me.