Section 1: Chapter 2

USMLE Biostatistics: Research Questions, Types of Variables, & Types of Data

In order to master USMLE biostatistics, you need to learn how to identify the main elements of medical research studies. Learn how to do this in this quick USMLE biostatistics lecture.

Chapter Objectives

Have you ever read a USMLE biostatistics question and found yourself completely lost, even after reading it multiple times? Although not always the case, most USMLE biostatistics questions require you to be able to identify fundamental research elements such as the research question, types of study variables, and types of data. If you understand these three things, then you will have a great advantage when it comes to reading and understanding USMLE biostatistic question stems. In this short chapter we will go over how to critically analyze medical research studies, especially in the context of the USMLE Step 1 and Step 2 CK. We will cover the following fundamental biostatistics and health research topics. 

  • Identifying and understanding the research question; what is the purpose of the study and what is it trying to answer?
  • Identifying and understanding the main study variables; what is the independent variable?
  • Identifying and understanding the main study variables; what is the the dependent variable?
  • Identifying and understanding the main study variables; what is the confounding variable?
  • Classifying the study data; what is qualitative data?
  • Types of qualitative data: Nominal data & Ordinal Data
  • Classifying the study data; what is quantitative (categorical) data?
  • Types of quantitative data; Interval data, Ratio data, & Discrete data
  • Implications of using quantitative data vs qualitative data; why is it important to classify the type of data used in the study?
In the next chapter, chapter 3, we will take an in depth analysis of important concepts in medical research which you must know for the USMLE. These concepts are validity (internal and external validity), reliability (aka reproducibility), accuracy and precision, accessing study validity, & the threats to internal and external validity. 

Chapter Details

  • Video length: 17 min 
  • Practice exercises: 7 USMLE style multiple choice questions
  • Estimated time to complete video lecture and practice exercises: 35 min 
  • Next chapter: Chapter 3 – Precision, Accuracy, Reliability, Internal validity & External Validity 

video

Thanks for watching our lecture! Solidify everything you have just learned by completing some USMLE style practice questions! Click the link below!

 

References:

Fletcher, G. S. (2012). Clinical epidemiology: The essentials [5th Edition]. Philadelphia ; Baltimore ; New York: Wolters Kluwer. Retrieved from https://meded.lwwhealthlibrary.com/book.aspx?bookid=735

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