What is the distinction between a cohort study and a case control study?
This study is a random stratified quantitative survey. To better understand we'll break it down to the components. The random portion is given in the study problem, it is sent to random people. The stratified group is a portion of the population separated from the remainder based on some characteristic defined by the researcher. In this case belonging to the medical group is the stratified population. It is quantitative in nature because the answers will be put into a numerical or data centric device to gauge response. A qualitative survey allows subjects to input their own data, whereas quantitative it is provided for by the researcher.
Let me try to clear things up. A Cohort study is a particular type of study generally used in the medical field to link causes with effects over time. The pictures you provided in your original question appear to be exactly this type of study. I may have gone a little further in breaking down the exact type of study you meant.
A case control study on the other hand is a study type where particular cases are selected for review are taken along with a control group. For example, selecting people taking a medication and then comparing to see if they have more birth defects compared to people not taking the medication.
The random nature of your case scenario means it is a cohort study designed to long term health care questions. The pros and cons of the study remains the same. Cohort can have disputed results due to other concerns being present the researcher is not aware of. In addition, merely being part of a study can encourage healthier lifestyles and effect the natural results as well.