Biostatistics Practice Questions

Q: The following statistical diagram is called

Funnel plot. ***Funnel plot*** - The diagram shows a **scatter plot** of studies arranged by **trial size (number of subjects)** on the y-axis and a measure of effect (implied effect size, typically odds ratio, risk ratio, or difference in means) on the x-axis, resembling an inverted funnel. - This characteristic funnel shape is used to visually assess **publication bias** or heterogeneity among studies in a meta-analysis. *Forest plot* - A **forest plot** displays the results of individual studies and their combined effect estimate, often represented by squares and a diamond. - It does not have the "funnel" shape seen in the provided image. *Box and whisker plot* - A **box and whisker plot** graphically displays the distribution of numerical data through their quartiles, showing the median, interquartile range, and potential outliers. - It is used to summarize dataset distributions and does not resemble the shown plot. *Stem and leaf plot* - A **stem and leaf plot** is a method for displaying quantitative data in a way that preserves original data values and provides a visual representation of their distribution. - This plot organizes data by separating observed values into a stem (leading digit) and a leaf (trailing digit), which is distinctly different from the given image.

Q: The following statistical diagram is called

Box and whisker plot. ***Box and whisker plot*** - This diagram displays the **distribution** of a dataset through **quartiles**, with the "box" representing the interquartile range (25th to 75th percentile) and the "whiskers" extending to the minimum and maximum values (or a specified percentile range). - The horizontal line inside each box indicates the **median** of the data, providing a visual summary of central tendency and spread for different categories. *Forest plot* - A forest plot is typically used in **meta-analyses** to display the results of multiple studies measuring the same outcome. - It shows **individual study estimates** and their confidence intervals, along with an overall pooled estimate. *Funnel plot* - A funnel plot is used to assess **publication bias** in meta-analyses. - It plots the effect size against a measure of study precision, and in the absence of bias, the plot should resemble a symmetrical inverted funnel. *Stem and leaf plot* - A stem and leaf plot is a way of organizing numerical data to show its **distribution** while retaining the individual data points. - It separates each data point into a "stem" (the leading digit(s)) and a "leaf" (the trailing digit).

Q: The following statistical diagram is called

Stem and leaf plot. ***Stem and leaf plot*** - This diagram displays quantitative data by separating each value into a "stem" (first digit(s)) and a "leaf" (last digit), arranged in order. - The provided image clearly shows digits on the left serving as stems (e.g., 1, 2, 3) and corresponding digits on the right as leaves (e.g., 80, 40, 60, 70), indicating a stem and leaf plot. *Forest plot* - A forest plot graphically presents the results of a **meta-analysis**, showing the estimated treatment effects and confidence intervals from multiple studies. - It does not organize individual data points by their numerical values in a stem-and-leaf structure. *Funnel plot* - A funnel plot is used to assess **publication bias** in a meta-analysis, plotting the effect size against a measure of study precision (e.g., standard error). - It appears as a scatter plot and does not resemble the structure of the given diagram. *Box and whisker plot* - A box and whisker plot displays the **five-number summary** of a set of data: minimum, first quartile, median, third quartile, and maximum. - It uses a rectangular "box" and "whiskers" extending from it, which is distinctly different from the digit-based organization seen in the image.

Q: The following statistical diagram is known as

Forest plot. ***Forest plot*** - This diagram, featuring a series of horizontal lines (representing **confidence intervals**) for different studies or outcomes, centered around a point estimate (often a **hazard ratio** or odds ratio), is characteristic of a forest plot. - Forest plots are commonly used in **meta-analyses** to graphically present the results of individual studies and their combined effect. *Kaplan Meier plot* - A Kaplan-Meier plot is a **survival curve** that shows the probability of a subject surviving beyond a certain time point. - It consists of a **stepwise function** decreasing over time, rather than individual point estimates with confidence intervals. *Spaghetti plot* - A spaghetti plot is used to display **multiple time series** on a single graph, where each line represents an individual's data over time. - This type of plot helps visualize **individual variability** and trends, but it does not represent hazard ratios or confidence intervals in the way shown. *Funnel plot* - A funnel plot is a scatter plot used to detect **publication bias** in meta-analyses, where the effect size is plotted against a measure of study precision. - It typically appears as a symmetrical, **funnel-shaped distribution** of points, which is visually distinct from the given diagram.

Q: A scatter diagram is shown below between two quantitative variables. Which of the following is the correct interpretation?

There is non-linear correlation between the two variables. ***There is non-linear correlation between the two variables*** - The data points in the scatter diagram clearly show a **pattern**, indicating a relationship between the variables. - However, this relationship is not a straight line; it curves upwards and then downwards, which defines a **non-linear correlation**. *There is correlation between the two variables and Pearson coefficient is 1* - While there is a **correlation**, the Pearson correlation coefficient of **1** implies a perfect positive linear relationship, meaning all points lie exactly on an upward-sloping straight line, which is not what is shown here. - The data points clearly deviate from a single straight line, showing both positive and negative trends at different stages. *There is correlation between the two variables and Pearson coefficient is -1* - The Pearson correlation coefficient of **-1** implies a perfect negative linear relationship, meaning all points lie exactly on a downward-sloping straight line. - The scatter plot shows a curved pattern, not a perfect negative linear trend. *There is no association between the two variables* - This statement is incorrect because the data points clearly show a **discernible pattern**, indicating that the variables are related. - If there were no association, the points would be scattered randomly with no clear trend or shape.

Q: Two laboratories have developed testing for Zika virus. The statistical method shown below was used to compare the diagnostic performance of these tests. What is this statistical method called?

ROC curve. ***ROC curve*** - This graph, displaying **true positive rate (sensitivity)** against the **false positive rate (1-specificity)**, is characteristic of a **Receiver Operating Characteristic (ROC) curve**. - ROC curves are commonly used to evaluate and compare the performance of **diagnostic tests** or predictive models across various threshold settings. *Lorenz curve* - A Lorenz curve is used in economics to represent **income inequality** or wealth distribution. - It plots the proportion of total income/wealth owned by the bottom x% of the population, and does not relate to diagnostic test performance. *Bell curve* - A bell curve, or **normal distribution curve**, is a symmetrical graph that shows the distribution of a **continuous variable**. - It describes how data points are distributed around the mean, not the performance of diagnostic tests. *Gaussian curve* - A Gaussian curve is another name for a **normal distribution** or **bell curve**. - It is used to model random variables in statistics, not to compare the sensitivity and specificity of diagnostic tests in the manner shown.

Q: A study was conducted to find out the number of positive lymph nodes in a population of breast cancer patients who underwent axillary dissection. A graph as shown below was plotted between the number and frequency of positive nodes. Which of the following is correct?

A: Mode, B: Median, C: Mean. ***A: Mode, B: Median, C: Mean*** - In a **positively skewed distribution**, the **mode** is the value that appears most frequently (highest peak), which is A. - The **median** is the middle value when data are ordered, and in a positively skewed distribution, it falls between the mode and the mean (point B). - The **mean** is the average of all values, and it is pulled towards the tail of the skew, making it the highest value among the three in a positively skewed distribution (point C). *A: Mean, B: Median, C: Mode* - This order would be correct for a **negatively skewed distribution**, where the tail extends to the left, and the mean is the smallest. - However, the given graph clearly shows a **positive skew**, with the peak at the beginning and the tail extending to the right. *A: Median, B: Mean, C: Mode* - This arrangement does not correspond to a standard distribution pattern, whether skewed positively or negatively. - The median, mean, and mode have established relative positions depending on the **skewness** of the data. *A: Mean, B: Mode, C: Median* - This option incorrectly places the **mode** in the middle and the **mean** at the beginning of the distribution. - This order is inconsistent with the characteristics of any common type of data distribution.

Q: In comparison of pulse oximeter reading in neonates with and without micropore, which of the following is true about the plot shown below?

Bland Altman plot. ***Bland Altman plot*** - This plot is used to **assess agreement between two different methods of measurement** by plotting the difference between the two measurements against their average. - The plot displays the **mean difference** (red line) and **limits of agreement** (+/- 1.96 standard deviation, blue lines), indicating how well the two SpO2 measurements agree. *Funnel plot* - A funnel plot is primarily used in **meta-analyses** to check for publication bias or small study effects. - It plots the **effect size** from individual studies against a measure of their precision (e.g., standard error). *Forest plot* - A forest plot is used in **meta-analyses** to graphically present the results of individual studies included in the review, along with the overall summary effect. - It typically shows the **effect estimate and confidence interval** for each study, and a diamond representing the pooled estimate. *Kaplan Meier plot* - This plot is used to estimate the **survival function** from lifetime data, showing the probability of an event (e.g., death, disease recurrence) occurring over time. - It is commonly used in **clinical trials** to compare survival rates between different treatment groups.

Q: A new test in red line has been designed to diagnose a disease condition. The test is applied to both normal and diseased population, the graph of which is given below. Which of the following is correct regarding the test?

Low sensitivity and low specificity. ***Low sensitivity and low specificity*** - In the provided graph, the **red line** curve (new test) for the healthy and diseased populations shows substantial **overlap**, meaning there is poor discrimination between the two groups. - A test with **low sensitivity** will miss many true positive cases (diseased individuals), and a test with **low specificity** will incorrectly identify many healthy individuals as diseased, both of which are indicated by the extensive overlap. *High sensitivity and high specificity* - This would be represented by two curves that are **well-separated**, with minimal overlap, allowing for clear distinction between healthy and diseased individuals. - Such a test would correctly identify most diseased individuals (**high sensitivity**) and most healthy individuals (**high specificity**). *High sensitivity and low specificity* - This would typically show a test that correctly identifies most diseased individuals (high true positive rate), but also incorrectly flags many healthy individuals as diseased (high false positive rate). - Graphically, this might appear as the diseased curve being mostly captured, but with significant spillover into the healthy range. *Low sensitivity and high specificity* - This scenario suggests a test that rarely misidentifies healthy individuals as diseased (low false positive rate), but also misses many diseased individuals (high false negative rate). - The healthy curve would be well-defined and distinct, but the diseased curve would significantly overlap with the healthy curve, indicating poor detection of disease.

Q: Sample size of samples A, B and C are 500, 800 and 1000 respectively. Which sample has the highest margin of error? (NEET Jan 2018)

Sample A. ***Sample A*** - The **margin of error** is inversely proportional to the square root of the sample size. Therefore, a smaller sample size leads to a larger margin of error. - Sample A has the smallest sample size (N=500) among the given options, thus having the **highest margin of error**. *Sample B* - With a sample size of 800, Sample B has a **smaller margin of error** than Sample A but a larger margin of error than Sample C. - As the sample size increases, the precision of the estimate improves, and the margin of error decreases. *Sample C* - Sample C has the largest sample size (N=1000), which results in the **smallest margin of error** among all samples. - A larger sample size generally provides a more accurate representation of the population. *None of above* - This option is incorrect because the sample size directly influences the margin of error, and Sample A clearly has the smallest size. - Based on statistical principles, one of the samples must inherently have the highest margin of error.

Question 1

The following statistical diagram is called

Accepted Answer

Funnel plot

Answer

Forest plot

Answer

Box and whisker plot

Answer

Stem and leaf plot

Question 2

The following statistical diagram is called

Accepted Answer

Box and whisker plot

Answer

Forest plot

Answer

Funnel plot

Answer

Stem and leaf plot

Question 3

The following statistical diagram is called

Accepted Answer

Stem and leaf plot

Answer

Forest plot

Answer

Funnel plot

Answer

Box and whisker plot

Question 4

The following statistical diagram is known as

Accepted Answer

Forest plot

Answer

Kaplan Meier plot

Answer

Spaghetti plot

Answer

Funnel plot

Question 5

A scatter diagram is shown below between two quantitative variables. Which of the following is the correct interpretation?

Accepted Answer

There is non-linear correlation between the two variables

Answer

There is correlation between the two variables and Pearson coefficient is 1

Answer

There is correlation between the two variables and Pearson coefficient is -1

Answer

There is no association between the two variables

Question 6

Two laboratories have developed testing for Zika virus. The statistical method shown below was used to compare the diagnostic performance of these tests. What is this statistical method called?

Accepted Answer

ROC curve

Answer

Lorenz curve

Answer

Bell curve

Answer

Gaussian curve

Question 7

A study was conducted to find out the number of positive lymph nodes in a population of breast cancer patients who underwent axillary dissection. A graph as shown below was plotted between the number and frequency of positive nodes. Which of the following is correct?

Accepted Answer

A: Mode, B: Median, C: Mean

Answer

A: Mean, B: Median, C: Mode

Answer

A: Median, B: Mean, C: Mode

Answer

A: Mean, B: Mode, C: Median

Question 8

In comparison of pulse oximeter reading in neonates with and without micropore, which of the following is true about the plot shown below?

Accepted Answer

Bland Altman plot

Answer

Funnel plot

Answer

Forest plot

Answer

Kaplan Meier plot

Question 9

A new test in red line has been designed to diagnose a disease condition. The test is applied to both normal and diseased population, the graph of which is given below. Which of the following is correct regarding the test?

Accepted Answer

Low sensitivity and low specificity

Answer

High sensitivity and high specificity

Answer

High sensitivity and low specificity

Answer

Low sensitivity and high specificity

Question 10

Sample size of samples A, B and C are 500, 800 and 1000 respectively. Which sample has the highest margin of error? (NEET Jan 2018)

Accepted Answer

Sample A

Answer

Sample B

Answer

Sample C

Answer

None of above

Biostatistics — MCQs

Biostatistics — MCQs

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