Lawson’s Classroom Test of Scientific Reasoning (LCTSR) is a widely used two-tier test in physics education. The effect of three scoring methods (separate, paired, and partial credit scoring) on the person ability measures obtained with the LCTSR and on the functioning of the test itself was investigated with Rasch analysis. LCTSR was administered to a sample of 98 prospective physics teachers from Faculty of Science, University of Zagreb. Results show that statistically indistinguishable person measures were obtained with each type of scoring, but that the choice of scoring method impacted test length and targeting, and therefore also reliability and standard errors of person measures.