# Trajectory detective — 13:15–13:40

These are hypothetical descriptions, not extra data or trial conclusions. Work seated, with one card per group, then swap explanations.

A. Two diet groups begin at approximately the same mean. The Enhanced group gains weight faster. Most individual lines are roughly parallel within diet. What does treatment × time represent? What varies between calves?

B. Both diets gain rapidly initially and more slowly later. The diet difference increases steadily. Why might a straight line miss the common trend? Would one common quadratic term allow different treatment slopes?

C. Mean trajectories look similar, but several calves show above-predicted weight for several neighbouring visits. Could errors from nearby visits still be related after fitting the average curve? What extra measurements would help distinguish a calf that grows faster throughout from short runs of above-predicted weights?

D. A calf has only its first three visits because later measurements are missing during illness. Why might available data tell a different story from complete follow-up? Would deleting all incomplete calves solve the problem? Name information needed before recommending an analysis.

Each group draws two trajectories, writes one candidate mean structure and states one limit. Do not fit the hypothetical cards. Our shared fixture is complete and has five visits per calf; real missingness requires additional investigation.