Final answer:
Without more context, it is not possible to provide the exact required follow-up rate for all eligible analytic cases. Sampling variation is likely the cause of the observed discrepancies in vaccination rates, and the confidence interval aim is usually around 90 percent.
Correct option is 3) 90
Step-by-step explanation:
The question regarding the required follow-up rate for all eligible analytic cases since the registry's reference date appears to be related to a particular data registry standard or policy, which is not provided in the question details. Therefore, it is not possible to give an accurate specific number without more context.
In the given examples, different rates of vaccination and disease diagnosis are observed in samples, which is a common issue in medical research. A discrepancy, like finding that 84 percent and 86 percent of children are up to date on their vaccinations, can be due to variation in sampling. Such variations can occur naturally due to the randomness inherent in taking a sample from a population.
When talking about the confidence interval for population mean, researchers often aim for a 90 percent confidence level, but the actual percentage that contains the population mean can vary based on the sample and the method used.