LBG - FS2024 – Exercise 4

Problem 1: Analysis of residuals

Use the dataset on weaning weight for beef cattle to fit a fixed linear model. Hence in this first analysis any random effects besides the residuals such as breeding values are currently ignored. In the fixed linear model Weaning Weight is used as response variable. Breast Circumference is used as regression predictor variable and Herd is used as fixed effect.

After fitting the fixed linear model, plot the residuals against the fitted values and see by visual inspection whether you can find any internal structure in the data.

The dataset is available from

https://charlotte-ngs.github.io/lbgfs2024/data/beef_data_bc.csv

Solution

• Start by reading the data

• Fit a fixed linear model

• Plot residuals against fitted values

Groups of points can be identified which most likely belong to animals which are related to each other.