BCPS – Biostats examination practices
with the best marking schemes 2024
Two types of random variables - Correct answer discrete and continuous
Discrete variables - Correct answer nominal, ordinal
Nominal variable - Correct answer unordered manner, no relative severity (e.g. male or
female sex, mortality, disease presence (y/n), race, marital status)
Ordinal variable - Correct answer ranked in specific order, no consistent level of
magnitude of difference between ranks (e.g. NYHA functional class)
Discrete variables: Common error - Correct answer Measure of central tendency -
means and SDs should not be reported with ordinal data
Continuous variables - Correct answer Interval, ratio
Interval variable - Correct answer data ranked in a specific order with a consistent
change in magnitude between units (the zero point is arbitrary (e.g. degrees Fahrenheit)
Ratio variable - Correct answer Like 'interval' but with an absolute zero (degrees Kelvin,
heart rate, BP, time, distance)
Descriptive statistics - Correct answer used to summarize and describe data that are
collected or generated in research studies (done both visually and numerically)
Descriptive statistics: Visual methods - Correct answer Frequency distribution,
histogram, scatterplot, boxplot
