In an experimental setup the independent variable is the one which can be changed and manipulated in an experiment the effect of which is observed on the dependent variable (s). The dependent variable is the one which cannot be manipulated in an experiment instead the changes occurring in a dependent variable are because of the manipulation of the independent variable. The dependent variable represents the outcome of the experiment.
According to the given situation, type of feed is the independent variable this is because of the fact that the there were two type of feeds were used one was experimented feed other was regular feed. The effect of both type of feeds has been observed on the weight of the cow which is the dependent variable.
The studies are designed this way b/c it removes the power of suggestion and the double-blind study keeps both researchers and participants in the dark. So this compared to who is receiving the treatment which is relevant b/c it stops the researchers from accidentally overbalancing the study participants, or unintentionally favoring their assessment of the conclusions.
