This study examines survey data from 2127 undergraduate women at the 2015 and 2019 American Physical Society Conference for Undergraduate Women in Physics (CUWiP) in order to classify what led them to study physics. We use expectancy-value and self-efficacy theory to create a coding framework based on different types of value and efficacy expectations in order to group responses. We find that the most common attractions are social persuasion, which is due to pressure or persuasion from people around the students, and intrinsic value, which is related to the inherent value of engaging in physics. Once the responses have been classified, we examine a follow-up survey to study whether the different motivational factors affect retention. We find that students who join physics because of the community are less likely to remain in physics after finishing their undergraduate studies. This is the first stage of a longer project to study which qualities correlate with retention in undergraduate women.