A limitation is that there are methodological issues into research. The investment model is supported by studies using self-report methods such as questionnaires. These may be affected by social desirability bias. However, what may matter more is a person's perception about how much investment they have made or how attractive their alternatives are. Therefore, the use of self-report measures may be appropriate because they assess partners' subjective perceptions about relationships, which are the most important influences on commitment.