1 / 10

ANCOVA

ANCOVA. One continuous Y variable. One or more continuous X variables (covariates). One or more class variables (treatments). Model: (Y-GM Y ) = (Y-Y’) + B (X-GM X ) + e Y = m j + B (X- GM X ) + e. Use of ANCOVA. Increase sensitivity of ANOVA.

truda
Download Presentation

ANCOVA

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. ANCOVA • One continuous Y variable. • One or more continuous X variables (covariates). • One or more class variables (treatments). • Model:(Y-GMY) = (Y-Y’) + B (X-GMX) + eY = mj + B (X- GMX) + e AGR206

  2. Use of ANCOVA • Increase sensitivity of ANOVA. • Adjust the treatment means to what they would be if all were at the average value of X. • In MANOVA (not considered any further). AGR206

  3. Assumptions • Normal, independent and equal-variance errors. • X is not affected by treatments. • Relationship between Y and X’s does not need to be linear. • Homogeneity of slopes. The model that relates Y to X’s must be the same for all groups (except for intercept). AGR206

  4. Example: 3 treatments New sales Previous sales AGR206

  5. Uncorrected ANOVA AGR206

  6. ANCOVA AGR206

  7. HW06 Solution AGR206

  8. HW06 Solution AGR206

  9. HW06 Solution AGR206

  10. HW06 Solution AGR206

More Related