A researcher develops an advertisement aimed at increasing how much the public trusts a federal organization. She asks participants to rate their level of trust for the organization before and after viewing an advertisement. Higher ratings indicate greater trust. From the following findings reported in APA format, interpret these results by stating the research design used (repeated-measures or matched-pairs), the sample size, the decision, and the effect size.
Participants rated the federal organization as significantly more trustworthy (MD = +4 points) after viewing the advertisement, t(119) = 4.021, p < .05, d = 0.88.