1 / 12

Fitting Several Regression Lines

Xuhua Xia. Fitting Several Regression Lines. The muscle strength (MS) depends on the diameter of the muscle fiber and the type of muscle (TM).Identify DV and IV.How do we incorporate the qualitative variable in to the model? The dummy variables.. TMDMSA111.5A213.8A314.4A416.8A518

base
Download Presentation

Fitting Several Regression Lines

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. Xuhua Xia Fitting Several Regression Lines Many applications of statistical analysis involves a continuous variable as dependent variable (DV) but both continuous and categorical variables as independent variables (IV). Relationship between DV and continuous IVs is linear and the slope remains the same in different groups: ANCOVA. Different slopes: Full model. An illustrative data set will make this clear.

    2. Xuhua Xia Fitting Several Regression Lines The muscle strength (MS) depends on the diameter of the muscle fiber and the type of muscle (TM). Identify DV and IV. How do we incorporate the qualitative variable in to the model? The dummy variables.

    3. Xuhua Xia Two Scenarios

    4. Xuhua Xia Two Scenarios

    5. Xuhua Xia Plot of MS vs D by TM

    6. Xuhua Xia Objectives Obtain regression equations relating MS to D for each TM. Compare the mean MS for the three TMs at a given level of D.

    7. Xuhua Xia SAS Program

    8. Xuhua Xia Explaining the SAS Program

    9. Xuhua Xia SAS Output

    10. Xuhua Xia SAS Output

    11. Xuhua Xia The Fitted Model The fitted dummy variable model is MS = 9.49 + 0.33 DUMA - 0.02 DUMB + 3.35 D - 1.61 DUMA*D - 2.00 DUMB*D Equations for individual TMs are A: MS = 9.49 + 0.33 + 3.35*D - 1.61*D = 9.82 + 1.74*D B: MS = 9.49 - 0.02 + 3.35*D - 2.00*D = 9.47 + 1.35*D C: MS = 9.49 - 0.00 + 3.35*D - 0.00*D = 9.49 + 3.35*D This individual equations can be used for prediction (e.g., estimating mean MS for D=3.5 for TM=A).

    12. Xuhua Xia Illustration with EXCEL

More Related