We study to learn something new. The word “study” in statistics implies conducting an experiment and analyzing data to learn something new, investigate something, or draw confident conclusions.
Studies are prevalent in medical fields, where people study various types of drugs on different demographics, geographies, and health conditions. This blog essentially contains my notes from the Coursera course: “Clinical Research” (https://www.coursera.org/learn/clinical-research/home/welcome).
Types of Studies:
- Observational Studies:
- Case Series Study: Observes and describes subjects without requiring a research hypothesis. Numbers derived from such studies help remove inherent biases. These studies often serve as initial steps for complex studies.
- Reference: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4297380/
- They took HIV positive children of age less than 13
- Look at the result section to see description.
- Case Control Studies: Compare two or more groups based on the presence or absence of a disease. These studies look at historical data to identify variables that differ between the groups. Confounding, such as smoking in a study on alcohol and heart attacks, needs to be controlled for.
- Many times when you are presenting analysis experienced seniors would ask what was the value of this feature in both cases ?
- Cross-Sectional Studies: Conducted in the form of surveys, gathering data at a specific time. For example, a survey sent to optometrists and ophthalmologists to understand their dietary advice to patients. These studies aim to examine current practices and identify areas for improvement. (Reference: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3695797/)
- Drawbacks
- Responsive bias
- Suppose you are asking questions related to HIV. Positive patients are less likely to answer than negative ones.
- In govt survey people in cities are more likely to answer than villages
- Almost impossible to infer causality
- Since this takes place at a particular place in time, we can not determine whether disease outcome followed exposure or exposure followed disease.
- Responsive bias
- Drawbacks
- Cohort Studies: Identify a group of subjects (cohort) and follow them either backward in history (retrospective cohort) or forward in the future (prospective cohort). Computerized data collection has made retrospective cohorts possible. These studies are observational and do not involve controlling variables.
- Case Series Study: Observes and describes subjects without requiring a research hypothesis. Numbers derived from such studies help remove inherent biases. These studies often serve as initial steps for complex studies.
- Experimental Studies (Interventional):
- In these studies, interventions are implemented to reduce bias inherent in observational studies. There is a control group that receives no intervention (sham/placebo).
- Some Key Terms:
- Randomization: Every member of the population should have an equal opportunity to be part of the study, and participants should have an equal chance of being assigned to any group.
- Blinding: Participants are unaware of their assigned groups. If researchers are also unaware of the groups, it is called a double-blind study. Achieving double-blindness is challenging in surgical operations.
Data Stories 