Vitamin C and zinc play important roles in nutrition, immune defense, and mainte
ID: 3208879 • Letter: V
Question
Vitamin C and zinc play important roles in nutrition, immune defense, and maintenance of health. Lately studies have been conducted to see if those compounds are effective against the common cold. One of those studies (Maggini, S., et al. A Combination of High-dose Vitamin C Plus Zinc for the Common Cold. Journal of International Medical Research. 2012. 40:28-42) reported a double-blind, randomized, placebo-controlled pilot study conducted in 64 patients with common-cold symptoms who were given either 1000 mg vitamin C & 10 mg zinc (32 patients), or a placebo (32 patient). Patients were monitored by a health care professional for symptoms such as rhinorrhea (runny nose: yes or no), cough (yes or no), throat irritation (yes or no), and temperature (degrees F). The results of evaluating the patients for the presence or absence of rhinorrhea are in the graph. Graph title: Results of Evaluating Patients for Rhinorrhea. The y axis is the percent of patients who had no symptoms. Is the study an observational study or an experiment? Specifically in this study (do not give general definitions), what are the experimental units (abbreviated EU, also called individuals or subjects) response variables and whether they are quantitative or categorical treatments How were the experimental units assigned to treatments? What does double-blind mean? What are the results of the study in terms of the response variable in the graph?Explanation / Answer
A. Experimental:
The given study was an experimental study becuase the investigator is randomizing a subject to one of the study drug and experimenting on the same on subjects.
Where as observational study is defined as just an overview of what's happening in the population without any intervention on subjects.
B. Experimental Units:
Experimental Units are individuals or subjects who are randomized to recieve one of the study treatments. In this study, the subjects who were randomized to the study treatments are pateints with common-cold symptoms. Hence, the experimetal units for this study are patients with common-cold symptoms
C. Response Variables
Response variables are variables which are outcome of interest in the study. Hence, the response variables of this study are
Rhinorrhea: Categorical Variable
Cough: Categorical Variable
Throat irritation: Categorical Variable
Temperature: Quantitative Variable
D. Treatments
Treatment which is given to the subjects in the study is 1000 mg Vitamin C and 10 mg Zinc.
E. Assignment of EU to treatments:
The treatments to EU are assigned randomly. That is each subjects will be randomized to one of the study treatment. So that each individual will have equally likely chance of getting either of the treatment.
F. Double-Blind
Double-blind means, the subjects and the drug administrator will be blinded. That is, subjects or EU who recieves the study treatment and the administrator of the drug who gives the drug to the subjects will be blinded so that no one will know what treatment was assigned to the subjects which will be eradicate the placebo bias.
G. Results from the graph
From the graph, we could see that as the treatment days increases, there is an increase in the percentage of the patients who had no symptoms of Rhinorrea.
Hence, the subjects who
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