An agricultural scientist wants to investigate the effect of a new dietary probiotic supplement on the milk production of dairy cows. He recruits 30 Holstein cows and randomly assigns them to two groups. Group A's daily feed is supplemented with 50g of the probiotic, while Group B receives a standard daily feed with 0g of the probiotic. After a four-week trial period, the daily milk yield (measured in litres) of each cow is recorded.
Write a suitable directional hypothesis for this investigation.
689 exam-style questions on AQA A Level Psychology Scientific processes. Each one has a worked solution and a mark scheme showing where the marks go.