A scientist wishes to determine how effective a vaccine is in protecting rats against a contagious disease. What experimental procedure should the scientist use to determine the vaccine's effectiveness?
Shouldn't she vaccinate half the rats and then expose all of them to the disease?
give vaccinations to 50 of the 100 rats and then expose all 100 to the disease
Give vaccinations to 50 of the 100 rats and then expose all 100 to the disease
Vaccinate 50 of the rats then expose only the 50 vaccinated rats to the disease
To determine the effectiveness of a vaccine in protecting rats against a contagious disease, the scientist should use a controlled experiment. Here's a step-by-step procedure the scientist can follow:
1. Sample selection: Randomly divide the rats into two groups: the control group and the vaccinated group. The two groups should be similar in terms of age, gender, and general health.
2. Baseline measurements: Before administering the vaccine, measure and record baseline data for both groups. This could include the rats' weight, temperature, and any other relevant indicators of health.
3. Administration of vaccine: Administer the vaccine to the rats in the vaccinated group following the recommended dosage and schedule. The rats in the control group should not receive the vaccine and should be given a placebo instead.
4. Exposure to the disease: Introduce the contagious disease to both the control and vaccinated groups, ensuring that the exposure conditions are the same for both groups. This can be done by either direct contact with infected rats or by exposure to a contaminated environment.
5. Observation and data collection: Monitor the rats in both groups for a specified period of time. Record any signs of infection or disease progression, such as symptoms, mortality rates, or time to recovery. It is important to employ blind or double-blind methods, if possible, to reduce bias during data collection.
6. Statistical analysis: Analyze the collected data using appropriate statistical methods. Compare the infection rates, severity of symptoms, mortality rates, and recovery times between the control and vaccinated groups.
7. Interpretation of results: Evaluate the data to determine the effectiveness of the vaccine. If the vaccinated group shows significantly lower infection rates, milder symptoms, lower mortality rates, or faster recovery times compared to the control group, it suggests that the vaccine is effective in protecting rats against the contagious disease.
8. Repeat and peer review: It is crucial to repeat the experiment multiple times to ensure the reliability of the results. Moreover, the findings should be subject to peer review to validate the scientific rigor and accuracy of the study.
By following this experimental procedure, the scientist will be able to determine the overall effectiveness of the vaccine in protecting rats against the contagious disease in a controlled and unbiased manner.