JASP Lesson 29 One Factor ANOVA Facebook Friends Trend Analysis with Orthogonal

This lesson focuses on the use of orthogonal polynomial contrasts for testing trends. Data are used where a quadratic effect is hypothesized. Contrast codes are shown that will test linear, quadratic, cubic, and quartic effects for a design with 5 levels. The video shows how directly testing the expected quadratic effect is more powerful and more appropriate than using post-hoc tests.