A strength of filter theory is it is supported by evidence
Kerckhoff and Davis (1962) studied 94 dating couples (students) in the US and found that: Similarity of attitudes was most important in relationships of less than 18 months. Complementarity of needs was more important in longer-term relationships.
This shows that some concepts from filter theory are supported by non-experimental research but it suggests that there one might be more significant than the other depending on the length of relationship.
This means that we can be confident that filter theory plays a role in attraction for relationships.
However, this evidence only tells us about the role of filter theory in American couples. Similarity/complementary might be a cultural value that might not be the same across cultures. This suggest that filter theory is vulnerable to beta bias as it assumes similarity across cultures.
