In data science, we usually classify variables into two big types: Continuous(age), Categorical(sex).

What about the variables in clinical trials/statistics? How many different types do we have?

**Little goal:**

Today we will learn the six common types of variable in statistics?

How to use and present them in clinical trials?

**Continuous variable**: Numerical numbers that have an infinite number of values between any two values.

*Ex: Age, weight, height, BMI*

Numerical: summary of stats (mean, median, sd, variance, min,max, q1,q3)

Graphics: Histogram, box plot**Binary/dichotomous variables**: only take two values, either yes or no

*Ex: death flag, AE flag, Inclusion/Exclusion*

Numerical: Proportion tabulate

Graphics: Bar plot**Nomial/categorical variables**: More than 2 categories without order

*Ex: Race*

Numerical: Frequency Count

Graphics: Bar plot/ Pie chart**Ordinal variables**: Categories with order.

*Ex: AE grade(mild, moderate, severe, life-threatening, death)*

*Pain score(1,2,3,4,5)*

Numerical: Frequency Count

Graphics: Bar plot/ Pie chart**Count/Discrete Variables**: occurrences are countable infinitely

*Ex: Number of Leision*

Numerical: Frequency Count

Graphics: Bar plot/ Pie chart**Time to Event Variable**: Time from the origin to a specified event happens.

*Ex: Time to death*Numerical: Median, Pvalue, 95%CI

Graphics: Kaplan Meier Curve.

* TTE, survival analysis is a unique analysis in the clinical trials.

*bonus: Measure of locations is a fancy way of saying mean, sd, median.*

Happy studying!

*Special thanks to 77 for sharing the Havard catalyst classes!*