2.4. Questionnaire
To measure the effectiveness of the three variables mentioned above, we developed 2 questionnaires for the participants to complete before and after watching the three pairs of videos (The questionnaires passed the verification of Credamo, which evaluated their negative effect. Eligible Credamo users could access the surveys from the platform.The participants’ performance in both the pretest and posttest reflected changes in their breast-health literacy, thus reflecting the effect of three variables and testing our hypotheses. Questions on both the pretest and posttest consisted of single and multiple choices. To ensure that the behavior of watching the video is related to breast health knowledge rather than changes in awareness, we designed the pretest and posttest based on the knowledge points mentioned in the video. Participants can only improve their accuracy by watching the video carefully and understanding the corresponding knowledge points, which cannot be achieved only by strengthening their awareness. The options in the two tests roughly corresponded. For a couple of options distributed in the pretest and posttest, if a participant answered the former correctly and the latter wrongly, −1 was marked, meaning that his/her breast health literacy had decreased after watching the video; if a participant answered the former incorrectly and the latter correctly, 1 was marked, meaning that his/her breast health literacy had increased after watching the video; and if a participant’s answer to both the former and the latter were correct or incorrect, 0 was marked, meaning that his/her breast health literacy had not changed significantly after watching the video.