Biostatistics Practice Questions

Q: Which age group is NOT included in the numerator of the dependency ratio?

20 years age group. ### Explanation The **Dependency Ratio** is a demographic indicator used to measure the economic burden on the productive population. It expresses the relationship between the "dependent" population (those not typically in the labor force) and the "productive" population. #### 1. Why Option C is Correct The formula for the Dependency Ratio is: $$\text{Dependency Ratio} = \frac{(\text{Population aged 0–14 years}) + (\text{Population aged 65+ years})}{\text{Population aged 15–64 years}} \times 100$$ * **Numerator:** Includes children (0–14 years) and the elderly (65+ years). * **Denominator:** Includes the working-age or "productive" population (15–64 years). * **The 20-year age group** falls within the 15–64 range; therefore, it belongs in the **denominator**, not the numerator. #### 2. Why Other Options are Incorrect * **Option A (5 years) & Option B (10 years):** These fall into the **Young Age Dependency** category (0–14 years). They are considered economically unproductive and are included in the numerator. * **Option D (70 years):** This falls into the **Old Age Dependency** category (65+ years). These individuals are also included in the numerator. #### 3. NEET-PG High-Yield Pearls * **Total Dependency Ratio:** Sum of Young Dependency + Old Age Dependency. * **Demographic Dividend:** Occurs when the dependency ratio declines due to a bulge in the working-age population (15–64 years), potentially accelerating economic growth. * **India's Trend:** India is currently experiencing a "youth bulge," meaning the denominator is large, leading to a favorable (lower) dependency ratio. * **Key Age Cut-offs:** Always remember **15** and **65** as the transition points for this calculation.

Q: In calculating the Dependency Ratio, what is the numerator expressed as?

Population under 15 years and 65 years and above.. **Explanation:** The **Dependency Ratio** is a demographic indicator used to measure the economic burden on the productive portion of a population. It is defined as the ratio of "dependents" (those typically not in the labor force) to the "working-age" population. **1. Why Option D is Correct:** According to international standards (UN and WHO), the dependency ratio is calculated using the following formula: $$\text{Dependency Ratio} = \frac{\text{Population (0–14 years) + Population (65 years and above)}}{\text{Population (15–64 years)}} \times 100$$ * **Numerator:** Includes children (under 15) and the elderly (65+), who are considered economically inactive. * **Denominator:** Includes the working-age group (15–64 years). **2. Why Other Options are Incorrect:** * **Options A & C:** The cutoff for the pediatric age group in global statistics is consistently **15 years**, not 10. * **Option B:** While some developing countries (including India in certain national surveys) have historically used **60 years** as the threshold for the elderly, the **standard international definition** for the Dependency Ratio specifically uses **65 years**. For competitive exams like NEET-PG, the UN standard (65+) is the preferred answer unless "Old Age Dependency Ratio in India" is specifically specified. **3. High-Yield Clinical Pearls for NEET-PG:** * **Total Dependency Ratio:** Sum of Young Dependency (0-14) and Old-Age Dependency (65+). * **Demographic Dividend:** Occurs when the proportion of the working-age population (15-64) is high relative to dependents, potentially accelerating economic growth. * **India Context:** In the Indian Census, the elderly are often categorized as **60+**, but for the standardized Dependency Ratio formula, **65+** remains the academic gold standard. * **Child Dependency Ratio:** (0-14 years / 15-64 years) × 100.

Q: What method is used to estimate the percentage of children immunized in a community as per WHO guidelines?

Cluster random sampling. **Explanation:** The correct answer is **Cluster Random Sampling**. This method is the gold standard recommended by the WHO for the **Expanded Programme on Immunization (EPI)** to estimate vaccination coverage in a community. **Why Cluster Random Sampling?** In large populations, creating a complete list of every individual (sampling frame) is often impossible. Cluster sampling overcomes this by dividing the population into natural groups or "clusters" (e.g., villages or wards). The WHO specifically uses the **"30 x 7" cluster survey design**, where 30 clusters are randomly selected, and 7 children of the target age group are surveyed within each cluster, totaling a sample size of 210. This method is logistically easier, cost-effective, and highly efficient for field-based community medicine. **Analysis of Incorrect Options:** * **A. Multistage Random Sampling:** While cluster sampling is a type of multistage sampling, the WHO guidelines specifically mandate the cluster technique for EPI surveys. Multistage is a broader term used for national-level surveys like NFHS. * **C. Systematic Random Sampling:** This requires a complete list of the population and selecting every $n^{th}$ individual. It is impractical for immunization surveys in areas where house numbering or population registries are incomplete. **High-Yield Facts for NEET-PG:** * **WHO 30 x 7 Design:** Used to estimate immunization coverage within a ±10% margin of error. * **Primary Sampling Unit (PSU):** In this design, the **village or ward** is the PSU, not the individual child. * **Design Effect:** Cluster sampling usually has a higher sampling error than simple random sampling; this is compensated for by the "Design Effect" (usually taken as 2 for EPI surveys). * **Application:** Besides immunization, cluster sampling is also used for rapid assessment of health needs during disasters.

Q: What non-parametric test is used to compare three or more independent groups of sampled data?

Kruskal-Wallis test. ### Explanation **Correct Answer: C. Kruskal-Wallis test** The **Kruskal-Wallis test** is the non-parametric equivalent of the One-way ANOVA. It is used to compare the medians of **three or more independent groups** when the data is ordinal or not normally distributed. In medical research, this is often applied when comparing clinical scores (like pain scales) across multiple treatment groups where the sample size is small or the variance is unequal. **Analysis of Incorrect Options:** * **A. Chi-square test:** Used to compare **categorical (qualitative) data** between two or more independent groups. It assesses the association between variables rather than comparing means or medians of continuous data. * **B. Fisher's exact test:** A variation of the Chi-square test used for categorical data when the sample size is very small (specifically when any cell value in a 2x2 table is less than 5). * **D. McNemar test:** Used to compare **paired (dependent) categorical data**. It is typically used in "before-and-after" studies involving nominal data (e.g., presence or absence of a symptom after treatment). **High-Yield Clinical Pearls for NEET-PG:** * **Parametric vs. Non-parametric:** If the data is normally distributed, use **ANOVA** for >2 groups; if not, use **Kruskal-Wallis**. * **Paired Data:** For comparing >2 **dependent/related** groups (non-parametric), the **Friedman test** is used. * **The "Rule of Two":** To compare 2 independent groups, use the **Mann-Whitney U test** (non-parametric) or **Unpaired t-test** (parametric).

Q: In a case-control study, which of the following cannot be directly measured?

Relative risk. In a **Case-Control Study**, researchers start with the outcome (cases) and look backward to determine exposure. Because the study begins with people who already have the disease, the **Incidence** (number of new cases over time) cannot be calculated. **Why Relative Risk is the correct answer:** Relative Risk (RR) is the ratio of the incidence of disease in the exposed group to the incidence in the non-exposed group ($RR = \frac{I_e}{I_u}$). Since a case-control study does not provide the "population at risk" to calculate incidence, **Relative Risk cannot be directly measured.** It can only be estimated using the Odds Ratio, provided the disease is rare. **Analysis of Incorrect Options:** * **B. Incidence:** While incidence also cannot be measured, the question specifically targets the primary measure of association. In most NEET-PG contexts, RR is the classic answer for what cannot be derived from case-control data. * **C. Odds Ratio (OR):** This is the **primary measure of association** in case-control studies. It calculates the odds of exposure among cases versus controls. * **D. Cause and effect relationship:** While case-control studies are weaker than Cohort studies or RCTs for establishing causality (due to recall bias and lack of temporality), they can still suggest a relationship. However, the mathematical impossibility of calculating RR is the definitive epidemiological rule. **High-Yield Clinical Pearls for NEET-PG:** * **Case-Control:** Proceeds from **Effect to Cause**. Best for **rare diseases**. * **Cohort Study:** Proceeds from **Cause to Effect**. Can directly measure **Incidence, Relative Risk, and Attributable Risk**. * **Matching:** Used in case-control studies to eliminate **confounding factors**. * **Recall Bias:** The most common bias encountered in case-control studies.

Q: In a village of 1 lakh population, among 20,000 individuals exposed to smoking, 200 developed cancer. Among 40,000 individuals not exposed to smoking, 40 developed cancer. What is the relative risk of smoking in the development of cancer?

10. ### Explanation **1. Understanding the Correct Answer (B: 10)** Relative Risk (RR), also known as Risk Ratio, is the ratio of the incidence of a disease among the exposed group to the incidence of the disease among the non-exposed group. It measures the strength of association between a risk factor and a disease. **Formula:** $$RR = \frac{\text{Incidence among exposed (Ie)}}{\text{Incidence among non-exposed (Io)}}$$ * **Step 1: Calculate Incidence in Exposed ($I_e$):** $I_e = \frac{200 \text{ (cases)}}{20,000 \text{ (total exposed)}} = 0.01$ (or 10 per 1,000) * **Step 2: Calculate Incidence in Non-exposed ($I_o$):** $I_o = \frac{40 \text{ (cases)}}{40,000 \text{ (total non-exposed)}} = 0.001$ (or 1 per 1,000) * **Step 3: Calculate RR:** $RR = \frac{0.01}{0.001} = 10$ An RR of 10 signifies that smokers are 10 times more likely to develop cancer compared to non-smokers. **2. Why Other Options are Incorrect** * **Options A (20), C (5), and D (15):** These are incorrect mathematical derivations. They often result from common student errors such as dividing the total population by cases, comparing only the number of cases (200/40 = 5), or failing to account for the different denominators in the two groups. **3. NEET-PG High-Yield Pearls** * **Study Design:** Relative Risk is calculated from **Cohort Studies**. * **Interpretation:** * $RR > 1$: Positive association (Risk factor). * $RR = 1$: No association. * $RR < 1$: Negative association (Protective factor). * **Attributable Risk (AR):** Measures the impact of a risk factor. Formula: $\frac{I_e - I_o}{I_e} \times 100$. In this case, AR is 90%, meaning 90% of cancer in smokers is due to smoking. * **Odds Ratio (OR):** Used in Case-Control studies as an estimate of RR.

Q: What is the probability to achieve a live birth within a single cycle?

Fecundity. ### Explanation The correct answer is **Fecundity**. In demography and biostatistics, it is crucial to distinguish between the biological potential and the actual realization of birth. **1. Why Fecundity is Correct:** **Fecundity** is defined as the physiological capacity of a woman (or a couple) to participate in reproduction and achieve a **live birth** within a single reproductive cycle. It represents the biological potential for successful reproduction ending in a live neonate. **2. Analysis of Incorrect Options:** * **Fertility (Option A):** In medical statistics, fertility refers to the **actual reproductive performance** (the number of live births achieved) rather than the capacity. While fecundity is the *potential*, fertility is the *realization*. * **Fecundability (Option C):** This is a high-yield distractor. Fecundability is the probability of **conception** (becoming pregnant) within a single menstrual cycle. It does not guarantee a live birth, as the pregnancy may end in miscarriage or stillbirth. * **Sterility (Option D):** This is the absolute physiological inability to conceive or produce a live birth. It is the opposite of fecundity. **3. High-Yield Clinical Pearls for NEET-PG:** * **Fecundability vs. Fecundity:** Think of Fecundability as "Probability of Pregnancy" and Fecundity as "Probability of Live Birth." * **Total Fertility Rate (TFR):** The average number of children a woman would have if she were to pass through her reproductive years (15–49 years) bearing children according to age-specific fertility rates. * **Replacement Level Fertility:** The TFR at which a population exactly replaces itself from one generation to the next (Value = **2.1**). * **Net Reproduction Rate (NRR):** The number of daughters a newborn girl will bear during her lifetime. An NRR of **1** is the demographic goal for population stabilization.

Q: What is true regarding Pictogram?

Method to represent data to the 'man in the street'.. ### Explanation **Correct Answer: D. Method to represent data to the 'man in the street'.** A **Pictogram** is a visual representation of data using small pictures or symbols. Each symbol represents a specific number of units (e.g., a "person" icon representing 1,000 people). It is considered the most popular and simplest method of data presentation because it is easily understood by the general public, including those without a background in statistics—often referred to as the **"man in the street."** #### Analysis of Incorrect Options: * **Option A (Areas shaded with different colors):** This describes a **Choropleth Map**. These maps use different shades or colors to represent the density or prevalence of a disease in different geographical areas. * **Option B (Trends of events over time):** This describes a **Line Diagram** (or Line Graph). Line diagrams are the gold standard for showing chronological changes or trends (e.g., birth rates over decades). * **Option C (Pictorial diagram of frequency distribution):** This is a distractor. While a pictogram shows frequency, the standard pictorial representation of a frequency distribution is a **Histogram**. #### High-Yield NEET-PG Pearls: * **Simplest method for laymen:** Pictogram. * **Best for trends over time:** Line Diagram. * **Best for comparing two or more discrete categories:** Bar Chart. * **Best for showing parts of a whole (proportions):** Pie Chart. * **Correlation between two continuous variables:** Scatter Diagram (Dot diagram). * **Frequency distribution of continuous data:** Histogram. * **Frequency distribution of discrete data:** Bar Chart.

Question 1

Which age group is NOT included in the numerator of the dependency ratio?

Accepted Answer

20 years age group

Answer

5 years age group

Answer

10 years age group

Answer

70 years age group

Question 2

In calculating the Dependency Ratio, what is the numerator expressed as?

Accepted Answer

Population under 15 years and 65 years and above.

Answer

Population under 10 years and 60 years and above.

Answer

Population under 15 years and 60 years and above.

Answer

Population under 10 years and 65 years and above.

Question 3

In a surveillance center for Hepatitis in a low prevalence area, the initial method for testing Hepatitis B was single ELISA. This policy was changed to double testing in series. Which of the following parameters of the test would be affected?

Accepted Answer

Sensitivity and negative predictive value

Answer

Specificity and positive predictive value

Answer

Sensitivity and positive predictive value

Answer

Specificity and negative predictive value

Question 4

What method is used to estimate the percentage of children immunized in a community as per WHO guidelines?

Accepted Answer

Cluster random sampling

Answer

Multistage random sampling

Answer

Systematic random sampling

Answer

All of the above

Question 5

What non-parametric test is used to compare three or more independent groups of sampled data?

Accepted Answer

Kruskal-Wallis test

Answer

Chi-square test

Answer

Fisher's exact test

Answer

McNemar test

Question 6

What does the General Fertility Rate indicate?

Accepted Answer

The number of live births per 1,000 women of reproductive age (usually 15-49 years).

Answer

The average number of children a woman is expected to have in her lifetime.

Answer

A measure of the number of births in a population relative to the total population.

Answer

All of the above.

Question 7

In a case-control study, which of the following cannot be directly measured?

Accepted Answer

Relative risk

Answer

Incidence

Answer

Odds ratio

Answer

Cause and effect relationship

Question 8

In a village of 1 lakh population, among 20,000 individuals exposed to smoking, 200 developed cancer. Among 40,000 individuals not exposed to smoking, 40 developed cancer. What is the relative risk of smoking in the development of cancer?

Accepted Answer

10

Answer

20

Answer

5

Answer

15

Question 9

What is the probability to achieve a live birth within a single cycle?

Accepted Answer

Fecundity

Answer

Fertility

Answer

Fecundability

Answer

Sterility

Question 10

What is true regarding Pictogram?

Accepted Answer

Method to represent data to the 'man in the street'.

Answer

Areas are shaded with different colours.

Answer

Used to show the trends of events with the passage of time.

Answer

A pictorial diagram of frequency distribution.

Biostatistics — MCQs

Biostatistics — MCQs

On this page

Practice by Chapter

Want unlimited practice?