Variable Types in Statistics

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!


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