/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 34 In order for a vaccine to be eff... [FREE SOLUTION] | 91Ó°ÊÓ

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In order for a vaccine to be effective, it should reduce a person's chance of acquiring a disease. Consider a hypothetical vaccine for malaria-a tropical disease that kills between 1.5 and 2.7 million people every year. \(^{20}\) Suppose the vaccine is tested with 500 volunteers in a village who are malaria free at the beginning of the trial. Two hundred of the volunteers will get the experimental vaccine and the rest will not be vaccinated. Suppose that the chance of contracting malaria is \(10 \%\) for those who are not vaccinated. Construct a two-way table to show the results of the experiment if: (a) The vaccine has no effect. (b) The vaccine cuts the risk of contracting malaria in half.

Short Answer

Expert verified
The table for the scenario where the vaccine has no effect contains the figures: Vaccinated & contracted malaria: 20, Not vaccinated & contracted malaria: 30. The table for the scenario where the vaccine cuts risk in half contains the figures: Vaccinated & contracted malaria:10, Not vaccinated & contracted malaria:30.

Step by step solution

01

Calculation of number of individuals not vaccinated

From the total of 500 volunteers subtract the 200 who received the vaccine. So, the number of individuals who are not vaccinated is \(500 - 200 = 300\).
02

Table for vaccine having no effect

In this scenario, the vaccine does not reduce the risk of contracting malaria. For this case, the number of individuals within each group who contract the disease can be calculated as 10% of the population of that group. \n - Vaccinated and contracted malaria: \(10\% \times 200 = 20\) - Not Vaccinated and contracted malaria: \(10\% \times 300 = 30\) All the rest in each group didn't contract the disease. So in the table there should be these values: \n | - | Vaccinated | Unvaccinated | | --- | --- | --- | | Contracted Malaria | 20 | 30 | | Didn't Contract Malaria | 180 | 270 |
03

Table for vaccine cutting risk in half

In this scenario, the vaccine reduces contraction risk by half. This means we divide the percentage of contracting the disease for vaccinated individuals by 2. For vaccinated individuals, risk becomes: \(10/2 = 5\% \). For not vaccinated remains 10%. The people contracting the disease in each group are: - Vaccinated and contracted malaria: \(5\% \times 200 = 10 \) - Not vaccinated and contracted malaria: \(10 \% \times 300=30 \) All the rest in each group didn't contract the disease. So in the table there should be these values: \n | - | Vaccinated | Unvaccinated | | --- | --- | --- | | Contracted Malaria | 10 | 30 | | Didn't Contract Malaria | 190 | 270 |

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Experimental Design
Experimental design in medicine is crucial, especially when testing new treatments or interventions, such as vaccines. It involves planning and structuring an experiment to ensure that the data collected can answer specific research questions. The design determines the reliability and validity of the results. In the case of the malaria vaccine exercise, a simple but effective design is used.
  • Two groups are created: one receives the vaccine, and the other does not.
  • This approach allows for a straightforward comparison between the vaccinated and unvaccinated groups, facilitating the evaluation of the vaccine's efficacy.
The chosen sample size of 500 individuals is essential as well. A larger sample size can generally offer more precise estimates and increases the study's power to detect differences between the groups if they exist. Creating such designs involves ensuring randomness, for instance, randomly assigning individuals to either receive the vaccine or be part of the control group (those not vaccinated). This process helps minimize biases and ensures that differences in outcomes can reliably be attributed to the intervention itself and not to other external factors.
Probability and Risk Analysis
Understanding probability and assessing risk is fundamental to analyzing medical data. It includes determining the likelihood of an event occurring, such as contracting a disease. In our example, probability is used to calculate the number of people expected to contract malaria.
For instance, if the chance is 10% for unvaccinated individuals, it implies that on average 10 out of every 100 individuals will contract malaria. To calculate this, use the formula:
  • Number of people contracting malaria = Probability of disease occurrence × Total number of people
In the case when the vaccine's effectiveness cuts risk by half, we adjust the probability for vaccinated individuals to 5% (half of 10%). This type of risk-adjusted analysis helps health professionals and researchers make informed decisions about the intervention's effectiveness. Understanding how to modify and interpret these probabilities is key when evaluating medical data and making evidence-based conclusions.
Data Interpretation
The interpretation of data is a critical step in converting collected data into meaningful information. Once an experiment is conducted, one must interpret the data to determine the success and impact of the intervention.
In the malaria vaccine case, interpretation involves comparing the numbers of individuals who contracted the disease in both groups to understand the vaccine's effectiveness. Proper interpretation also highlights the real-world implications of the data, such as potential reductions in disease prevalence when vaccines are implemented on a larger scale.
  • The ability to read and understand two-way tables, like those created in the exercise, is essential for interpretation.
  • These tables help visualize the relationship between different groups (those vaccinated vs. not vaccinated) and their outcomes.
  • Being able to interpret such tables with clarity helps in communicating results and making informed public health decisions.
Data interpretation isn't just about reading numbers; it's about seeing the bigger picture the data presents, which, in this scenario, can guide future trials and healthcare policies.

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