Which of the following is dichotomous variable?

A dichotomous variable, also known as a binary variable, is a type of categorical variable that can have only two possible, mutually exclusive outcomes. In this question, "Sex" (when defined as male/female), "Pain yes/ Pain no," and "alive / dead" all represent variables with exactly two categories. These are fundamental data types used in biostatistics and clinical trials to represent the presence or absence of a condition, a specific outcome, or a demographic characteristic. Variables with more than two ordered categories, such as cancer grade or NYHA class, are classified as ordinal variables, not dichotomous.

D. Grade of Breast Cancer: This is an ordinal variable because it has more than two categories (e.g., Grade 1, 2, 3) that follow a specific order of severity.

E. NYHA I-IV: This is an ordinal variable representing the New York Heart Association functional classification, which has four distinct, ordered levels of heart failure severity.

1. Sullivan

L. M. (2018). Essentials of Biostatistics in Public Health (3rd ed.). Jones & Bartlett Learning. In Chapter 1

"Introduction and Data Presentation

" dichotomous variables are defined as categorical variables with two possible responses. Examples provided are consistent with sex (male/female) and yes/no outcomes.

2. Boston University School of Public Health. (n.d.). Data Presentation. In BS704: Introduction to Biostatistics course materials. Retrieved from https://sphweb.bumc.bu.edu/otlt/mph-modules/bs/bs704summarizingdata/bs704summarizingdataprint.html. Section: "Types of Variables". This resource explicitly lists "Sex (male

female)" and "CVD (yes/no)" as examples of dichotomous variables.

3. Rana

R. K.

& Singhal

R. (2015). Chi-square test and its application in medical research. Journal of Practice of Cardiovascular Sciences

1(1)

69. https://doi.org/10.4103/2395-5414.157577. This article discusses variable types in the context of statistical tests

defining dichotomous variables as those with two categories

such as "male/female" or "smoker/non-smoker."

4. PennState Eberly College of Science. (n.d.). STAT 200: Elementary Statistics - Lesson 1.2: Categorical & Quantitative Variables. Retrieved from https://online.stat.psu.edu/stat200/lesson/1/1.2. This courseware defines a binary (dichotomous) variable as a categorical variable with only two possible outcomes

providing "gender (male

female)" as a primary example.