Answer:
Explanation:
To determine the number of subjects needed to estimate the mean number of books read the previous year within six books with 90% confidence, you would need to use a sample size calculation. There are several factors that can affect the sample size needed, including the desired level of confidence, the desired level of precision, the variability of the population being sampled, and the size of the population.
One way to calculate the sample size is to use a sample size calculator, which can be found online or in statistical software. These calculators typically ask for the desired level of confidence, the desired level of precision, and the estimated standard deviation of the population being sampled.
Alternatively, you can use a sample size formula to calculate the sample size. For example, the formula for calculating the sample size for a simple random sample with a known population standard deviation is:
n = (Z*sigma / E)^2
where n is the sample size, Z is the z-score corresponding to the desired level of confidence (e.g., for a 90% confidence level, Z would be 1.645), sigma is the population standard deviation, and E is the desired level of precision (e.g., 6 books in this case).
To use this formula, you would need to know the population standard deviation, which may require collecting data from a pilot study or using estimates based on similar populations.
It's important to note that sample size calculations are based on statistical assumptions, and the actual sample size needed may vary depending on the specific characteristics of the population being sampled. Additionally, sample size calculations are based on estimates, so the actual level of precision may differ from the desired level.