Question

You have 1000 volunteers to find out if taking Zinc supplements at the first sign of a cold really shortens the duration and lessens the symptoms.

Describe how you would design an observational study to determine this.

Now describe how you would design an experiment to determine this.

Answer 1

(a)

An observational study :

Interview each volunteer and analyze the past medical records whether (i) the volunteer took Zinc supplements at the first sign of a cold (ii) What is the duration of the cold (iii) Did the symptoms lessen. After collecting such information, detailed statistical analysis can be carried out to find out if taking Zinc supplements at the first sign of a cold really shortens the duration and lessens the symptoms

(b)

An experiment :

Randomly assign the 1000 volunteers to 2 mutually exclusive groups, each consisting of 500 volunteers as follows:

(i) Treatment Group: in which each volunteer will be given Zinc supplements at the first sign of a cold

(ii) Control Group: in which each volunteer will be given a substance looking exactly like Zinc supplements but it will be a placebo at the first sign of a cold

After the experiment is completed, collect details such as (i) the participant took Zinc supplements at the first sign of a cold , i.e., whether the participant belongs to Treatment Group or Control Group: (ii) What is the duration of the cold (iii) Did the symptoms lessen.After collecting such information, detailed statistical analysis can be carried out to find out if taking Zinc supplements at the first sign of a cold really shortens the duration and lessens the symptoms