As is true of any self-report instrument, respondents can consciously distort their response to the scale if they are motivated to do so. For this reason, it is desirable to supplement the self-reported SWLS with assessments from external sources, such as informant SWLS or interviewer ratings, whenever possible.
The focus of the first three items of the SWLS is on a person’s current life, whereas the last two items inquire about how the person has previously been, up until the present. A discrepancy within the scores of the first three items and the last two items can reveal whether people view their lives as improving or declining.
The SWLS does not measure all aspects of Subjective Well-Being (SWB). It is a narrow-band instrument, intended to assess the cognitive rather than affective component of SWB. Although the cognitive and affective components of subjective well-being are obviously related, scores on the SWLS cannot automatically be used as direct measures of emotional well-being. Instruments with an affective focus should be included in research designs that are intended to obtain data on the broader construct of global SWB.