# Week 11 workshop record

Names and roles:

## Design and question
1. Researchers assign one diet to each calf and weigh it five times. Count the calves on each diet and the weight records. What would a sixth weighing add, and what would it leave unchanged?
2. Researchers record weight in kg and elapsed time in weeks. What units describe the extra weekly gain for Enhanced compared with Control?
3. For the week-8 comparison, say which calves and rooms you want the result to describe, give the weight units and name which diet is subtracted from which.

## Two defensible mean relationships
4. Sketch a straight mean trend and a curved common mean trend with different diet slopes.
5. Translate `diet * week + room` and `diet * week + I(week^2) + room` into words. Which term changes with diet? Which curvature is shared?
6. Read output for both fits. Keep one satisfactory feature and one concern. Inspect observed-minus-fitted weights against week, and consider whether a calf's errors at nearby visits may still be related.
7. Explain why improvement in mean shape may leave dependence. What further structure might need assessment? Supplied extension is optional to interpret; advanced fitting is not required.
8. Compare the estimated week-8 diet difference and approximate uncertainty. Does a narrower interval establish a better model? Does the fitted curve justify extrapolation to week 16?

## Project workshop, 15:10–15:45
9. Retrieve your saved Class 10 plan. Explain what researchers do to the animals or groups and what they measure. Say why your model suits those records, how it connects repeated or shared measurements, and which comparison answers your question. Record any change to your plan. If your project has no repeated weights, do not add calf time terms without a reason.
10. State one useful preliminary result and one concern raised by a model check. Suggest an alternative assumption worth comparing because of what researchers did or what is known about the animals. If code fails, show your proposed analysis and descriptive plot, and identify the calculation needing support.

## Individual exit
Explain why weighing 32 calves five times does not create 160 calves receiving a diet, and name one assumption that remains after adding a common quadratic time term.