#1
Which of the following is an example of a categorical variable?
Gender (Male/Female)
ExplanationCategorical variables represent characteristics that can be divided into groups or categories.
#2
Which type of sampling method involves selecting every kth individual from a list after a random start?
Systematic sampling
ExplanationSystematic sampling involves selecting individuals at regular intervals from an ordered list.
#3
What statistical measure is used to assess the strength and direction of a linear relationship between two continuous variables?
Correlation coefficient
ExplanationCorrelation coefficient quantifies the degree and direction of the relationship between two continuous variables.
#4
What type of study design is often used to investigate the prevalence of a health condition in a specific population at a single point in time?
Cross-sectional study
ExplanationCross-sectional studies collect data at a single point in time to determine the prevalence of a health condition.
#5
In statistical hypothesis testing, what is the significance level typically set at to determine statistical significance?
0.05
ExplanationThe significance level (alpha) is commonly set at 0.05, indicating a 5% chance of rejecting the null hypothesis when it is true.
#6
Which of the following is an example of a continuous variable?
Height in centimeters
ExplanationContinuous variables can take any value within a range and are often measured rather than counted.
#7
What is the purpose of randomization in experimental study designs?
To eliminate bias
ExplanationRandomization helps in distributing confounding factors equally among the groups, reducing bias.
#8
In a crossover study design, participants receive different treatments at different time points. What is the primary advantage of this design?
Reduces the impact of carryover effects
ExplanationCrossover design minimizes carryover effects by allowing each participant to serve as their control.
#9
In a clinical trial, what is the purpose of a placebo group?
To ensure blinding of participants and researchers
ExplanationPlacebo groups help in assessing the true effect of the treatment by controlling for psychological and physiological effects.
#10
What is the purpose of blinding in a research study?
To prevent bias in the assessment of outcomes
ExplanationBlinding ensures that participants and/or researchers are unaware of the group assignments or treatment being administered, reducing bias.
#11
In statistical terms, what does the p-value represent?
The probability of obtaining the observed results by chance alone
ExplanationThe p-value indicates the likelihood of obtaining the observed results if the null hypothesis is true.
#12
What is the purpose of stratification in epidemiological studies?
To increase the precision of estimates within subgroups
ExplanationStratification helps in controlling confounding variables by analyzing data within homogeneous subgroups.
#13
What is the main difference between observational and experimental study designs?
Experimental studies involve random assignment, while observational studies do not.
ExplanationObservational studies observe subjects in their natural environment without intervention, while experimental studies manipulate variables under controlled conditions.
#14
When analyzing a cohort study, what does the hazard ratio represent?
Risk of an event in the exposed group compared to the unexposed group over time
ExplanationHazard ratio measures the ratio of the hazard rates between two groups over time in cohort studies.
#15
In a factorial experimental design, how many independent variables are manipulated simultaneously?
Two
ExplanationFactorial design involves manipulating two or more independent variables simultaneously to study their combined effects.
#16
What is the purpose of a confounding variable in a research study?
To introduce bias and obscure the true relationship
ExplanationConfounding variables are extraneous factors that can distort the relationship between the independent and dependent variables.
#17
What is the primary advantage of using a cross-over design in clinical trials?
Reduces the impact of carryover effects
ExplanationCrossover design minimizes carryover effects by allowing each participant to act as their control, reducing variability.
#18
In statistical terms, what does the term 'power' refer to?
The ability of a study to detect a true effect when it exists
ExplanationPower measures the probability of correctly rejecting the null hypothesis when it is false, indicating the study's sensitivity to detect true effects.