Controlled experiments are those in which groups are separated into control and experimental. Neither group knows what they are receiving, so they may or may not be receiving a sugar pill or something else. The control group is essential for comparisons -- what happens in the control group often determines how the experimental data is interpreted (Scientific Control Group, 2008). A double blind experiment is one in which some of the participants are prevented from knowing certain information about the study that might lead to bias (conscious or subconscious) thus skewing the results. Blinding can also be imposed on researchers, subjects, funders, or any combination in which one wishes to protect the data integrity. In the use of new drugs, blinded experiments are necessary because a patient might feel better if they think they are receiving a powerful new medicine -- the placebo effect. It is impossible, however, to double blind all studies, for ethical and humanitarian reasons, for instance. Using double blind studies is one of the reasons 20th century science advanced -- observer bias can affect an experiment (Double Blind Experiment, 2008).

Part 1 -- C -- Based on the results of Study A, there seems no scientific reason for Max to take Vitamin C during the winter months. Both the control and experimental groups showed no difference in the disappearance of cold symptoms...

If Max is getting at least 90-100 mg of Vitamin C daily, his daily health, based on this study, is supplemented appropriately. If there are other reasons Max might wish to supplement his diet (e.g. excess stress, poor diet, excess caffeine), then there might be a reason for supplementation. But, if the reason is only to prevent the severity of a cold, and this Study is the basis for his research, then there is no reason for Max to supplement.
Part 2 -- A -- Study 2 was controlled, although perhaps not well controlled. We do not know the variables of the individuals in the study (age, exercise or health level, attitude, gender, etc.). We also do not know whether these individuals are susceptible to colds (liver issues, immune issues, etc.). For the control to be robust, the populations would need to be more alike, and the delineation of the variables of the participants would need to be disclosed; likely 20 individuals would not be a large enough experimental group. Finally, we only know that the subject consumed the same amount of dietary item C. And spent 4 hours in the same room; we do not know what they ate outside of the experiment, what environment they were in, how much rest they received, or how close they were to the individual with the cold. For instance, some might have felt a cold coming on, therefore drank more fluids and rested; this…