Question

Calculate the margin of error in estimating a binomial proportion \(p\) using samples of size \(n=100\) and the values of p given in Exercises \(15-19 .\) What value of p produces the largest margin of error? \(p=.5\)

Short answer

Answer: The value of p that produces the largest margin of error is 0.5, and the corresponding margin of error is 0.098.

Step-by-step solution

Identify the given values

We are given the following values: - Sample size, \(n = 100\) - Proportion, \(p = 0.5\) We will use \(z=1.96\) for a 95% confidence level.

Calculate the margin of error for the given value of p

We will use the formula for the margin of error (MoE) for a binomial proportion: \(MoE = z * \sqrt{\frac{p(1-p)}{n}}\) Plugging in the given values, we get: \(MoE = 1.96 * \sqrt{\frac{0.5(1-0.5)}{100}}\) Calculate the expression inside the square root: \(MoE = 1.96 * \sqrt{\frac{0.25}{100}}\) Now, calculate the square root: \(MoE = 1.96 * 0.05\) Finally, multiply by the z-score: \(MoE = 0.098\)

Identify the value of p that produces the largest margin of error

The exercise asks us to calculate the margin of error for different values of p, but we only have information for \(p=0.5\). However, the largest margin of error occurs when \(p=0.5\), as this value maximizes the expression inside the square root in the MoE formula (\(\frac{p(1-p)}{n}\)). Thus, the value of p that produces the largest margin of error is 0.5, and the corresponding margin of error is 0.098.

Key concepts

Binomial Proportion

Understanding the binomial proportion is crucial when dealing with statistics related to binary outcomes—situations where there are only two possible results, like a coin flip (heads or tails), a test result (pass or fail), or a response to a survey question (yes or no). The binomial proportion, denoted as \( p \), represents the likelihood of one particular outcome occurring.

For instance, let's say you want to find out the proportion of students who passed an exam. If 70 out of 100 students passed, the binomial proportion \( p \) would be 0.7 or 70%. Calculating the margin of error in this context gives us an understanding of the precision of our estimation of the binomial proportion, capturing the potential fluctuation if we were to repeat the study multiple times.

When you're estimating the true binomial proportion from sample data, you need to acknowledge that there is some uncertainty in your estimate. This uncertainty is quantified by the margin of error, which tells you how 'confident' you can be that the true proportion falls within a certain range around your estimated proportion.

Confidence Level

The confidence level of statistical analysis is a measure of how sure we can be that our results are accurate. To put it simply, it reflects our confidence in the probability that our estimate includes the true parameter we're trying to measure. This is not about the certainty of a single estimate being correct, but about how often the estimate would be correct if we repeated our study over and over.

The most common confidence level used is 95%, which is associated with a \( z \) score (a value from the z-distribution which corresponds to the desired confidence level) of approximately 1.96. This means that if we were to randomly sample the population many times, we would expect our calculated interval (estimate plus or minus the margin of error) to include the true population proportion in about 95 out of 100 samples.

In our exercise example, the 95% confidence level means that we are 95% confident that the true binomial proportion falls within 0.098 (the margin of error) of our sample proportion, \( p = 0.5 \), if we were to conduct the survey 100 times.

Sample Size

The sample size can have a significant impact on the results of a study. In statistics, the sample size is essentially the number of observations or replicates included in the analysis. A larger sample size generally results in a smaller margin of error, indicating a more precise estimate of the population parameter.

The relationship between sample size and margin of error is inversely proportional; as the sample size increases, the margin of error decreases, assuming the confidence level stays the same. This occurs because with more data, there's a better representation of the true population, leading to a higher chance that the sample mean will be close to the population mean.

Mathematically, the formula for the margin of error shows this relationship: \( MoE = z * \sqrt{\frac{p(1-p)}{n}} \), where \( n \) represents the sample size. In the step-by-step solution provided, you can see that the larger the value of \( n \), the smaller the value under the square root, which reduces the margin of error. This is why ample and representative samples are so important in statistical analysis; they provide more accurate and reliable results.