Asking about changes in happiness in a daily web survey

This paper investigates whether the level of happiness and integrated process of changes in happiness are the same. Using the daily data of two waves of four and six months each, we found that the level of happiness is stationary, whereas the integrated process of changes is non-stationary with a rising trend, implying that they are different series. An examination of the causes of the difference indicated that although adaptation completely influences the level of happiness, it only partially influences the change in happiness. This may be because the latter is based on a comparison between today and yesterday.