Conducting an Experiment at Multiple Sites with Small Subject Pools: How is Raven Score Effective as a Covariate? - Kazuhito Ogawa; Yusuke Osaki; Tetsuya Kawamura; Hiromasa Takahashi; Satoshi Taguchi; Yoichiro Fujii; Kengo Kurosaka; Kohei Iyori; Naoki Watanabe 001 (IEEE Big Data, 2023)