Study questions

The following questions refer to the protocol by Hanson and Fernandez-Rivera.

6. Under the paragraph headed Animals the authors describe how they will assign the lambs to experimental groups in a way that the interval and mean of initial weight will be similar across groups. What do you think the authors mean? Do you think that this will achieve satisfactory animal randomisation to accessions?

7. Under the paragraph headed Experimental design and data analysis the authors describe their proposed analysis for a completely randomised design with initial weight as a covariate. Do you think that they are justified in analysing the experiment in this way when they have grouped the lambs before randomising them? Investigate by fitting alternative models to the data in CS5Data3.

8. Under the paragraph headed Monitoring of experiment the authors describe how they will weigh the sheep three times at the start. Why do you think they want to do this? Describe two ways in which average daily gain might be calculated. Which would you recommend to the researchers?

9. Under the paragraph headed Experimental design and data analysis the authors refer to the experiment as being an 'exploratory non-replicated experiment'. Do you think that it is right to describe the experiment in this way? Describe how you might design a follow-up study. Which type of livestock would you use?

10. Review the protocol. Make any recommendations for improvement.