Question: The below is for a hypothetical study demonstrating the application of the concepts for superiority and non-inferiority testing.

A study investigated a new agent for the treatment of arthritis.Participants were randomized to receive either the current widely used (and effective) treatment or to the new experimental treatment. After 3 weeks they recorded if, based on a clinical assessment, there were improvements in symptoms (recorded as yeso). Because of the potential large impact of age the investigators used a multiple regression model to test for differences adjusting for age. (Technically since the outcome is binary they used what is called a logistic regression model, but the analytic approach is the same.)

Investigators want to test if the new treatment is non-inferior to the current treatment.

Treatment is coded as 0=usual treatment and 1=new treatment so that a positive coefficient represents greater improvement with the new treatment.The study was done on a large sample and you may use the normal distribution for testing coefficients.

Prior to testing the investigators selected (+) 0.40 for the non-inferiority parameter (8). Parameter Estimate Standard Error Intercept -2.57 1.11 Treat (B1) 0.52 0.46 age 0.03 0.02