- Mean self-reported pain scores: mixed randomized-repeated measures analysis of covariance (ANCOVA) with the randomized factors of treatment group (IV acetaminophen plus narcotics versus IV narcotics plus normal saline) and surgery type (LRYGB versus LSG); the repeated measures factor of pain scores over time (i.e., 2-hours intervals from 2 to 22 hours); and the first post-operative pain scale assessment as the covariate. Pain scores were measured on a numeric scale, with 0 representing no pain and 10 representing the worst imaginable pain. Prior to data analysis, the assumptions of normality of sampling distributions, homogeneity of variance, presence of significantly influential outliers, linearity between the baseline pain score covariate and subsequent pain scores, and homogeneity of regression for the covariate-outcomes slopes were evaluated. These assumptions were met with the exception of moderate heterogeneity of variance for the IV acetaminophen-LSG group for 10-hour pain scores and largely curvilinear relationships between the covariate and subsequent pain scores. Therefore, the covariate was logarithmically transformed, and a more conservative p-value < .025 was used to assess pain scores over time. In order to obtain a clearer understanding of the repeated measures main effect of pain scores over time, an additional analysis of variance excluding the covariate of baseline pain scores was also conducted.