of Biostatistics 8th Edition Rosner
Questions and Answers with rationales
Chapter 1: Introduction and Descriptive Statistics
Question 1
Define a population in the context of biostatistical research.
A) A subset of measurements chosen for analysis
B) The complete set of measurements of interest
C) Any group of individuals studied in an experiment
D) The sample data collected from a study
Correct Answer: B) The complete set of measurements of interest
*Rationale: A population is defined as the entire set of measurements or observations of
interest in a study. This is distinguished from a sample, which is only a subset of the
population .
,Question 2
What is the primary purpose of descriptive statistics?
A) To make predictions about future outcomes
B) To organize, condense, and summarize data into meaningful information
C) To prove causation between variables
D) To test research hypotheses
Correct Answer: B) To organize, condense, and summarize data into meaningful
information
*Rationale: Descriptive statistics involves constructing tables, graphical displays, and basic
statistical computations that condense and organize information into a set or figure that
can be easily understood .
Question 3
A researcher wants to estimate the prevalence of diabetes in a city. She collects
data from 500 randomly selected residents. The 500 residents represent a:
A) Population
B) Sample
C) Parameter
D) Variable
Correct Answer: B) Sample
*Rationale: A sample is a subset of the population that is selected to represent the larger
population. In this case, the 500 residents are a subset of the entire city population .
,Question 4
Statisticians who analyze data and make inferences about populations based on
sample data are called:
A) Data analysts
B) Biostatisticians
C) Epidemiologists
D) Clinicians
Correct Answer: B) Biostatisticians
*Rationale: Biostatisticians are professionals who analyze data and make inferences
about populations based on sample data. They guide the design of experiments and
surveys and estimate sample sizes to minimize study errors .
Question 5
Which of the following correctly distinguishes between a retrospective and
prospective study?
A) Retrospective studies gather past data; prospective studies gather future data
B) Retrospective studies are always experimental; prospective studies are always
observational
C) Retrospective studies are more reliable than prospective studies
D) Prospective studies gather past data; retrospective studies gather future data
Correct Answer: A) Retrospective studies gather past data; prospective studies
gather future data
, *Rationale: Retrospective studies gather past data to determine a difference (case-control
studies). Prospective studies follow subjects forward in time to observe outcomes .
Question 6
Incidence rate is defined as:
A) The number of existing cases of disease in a population
B) The number of newly diagnosed cases divided by the number of persons at risk
C) The number of deaths due to disease divided by total population
D) The number of cases in population divided by total population
Correct Answer: B) The number of newly diagnosed cases divided by the number of
persons at risk
*Rationale: Incidence rate measures the number of newly diagnosed cases of a disease in
a population during a specific time period. This differs from prevalence, which measures
existing cases .
Question 7
Prevalence rate is calculated as:
A) Number of newly diagnosed cases divided by person-years at risk
B) Number of cases in population divided by total population
C) Number of deaths due to disease divided by total population
D) Number of cases divided by number at risk
Correct Answer: B) Number of cases in population divided by total population