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91Ó°ÊÓ

In a study to compare the perceived effects of two pain relievers, 200 randomly selected adults were given the first pain reliever, and \(93 \%\) indicated appreciable pain relief. Of the 450 individuals given the other pain reliever, \(96 \%\) indicated experiencing appreciable relief. a. Give an estimate for the difference in the proportions of all adults who would indicate perceived pain relief after taking the two pain relievers. Provide a bound on the error of estimation. b. Based on your answer to part (a), is there evidence that proportions experiencing relief differ for those who take the two pain relievers? Why?

Short Answer

Expert verified
The estimate for the difference is 0.03; the interval \((-0.0266, 0.0866)\) includes 0, indicating no significant difference.

Step by step solution

01

Calculate Proportions

First, calculate the proportion of individuals who reported pain relief for each pain reliever. For the first pain reliever: \( \hat{p}_1 = \frac{93}{100} = 0.93 \). For the second pain reliever: \( \hat{p}_2 = \frac{96}{100} = 0.96 \).
02

Estimate Proportion Difference

Find the difference in proportions between the two groups: \( \hat{p}_2 - \hat{p}_1 = 0.96 - 0.93 = 0.03 \). This difference indicates how much more effective the second pain reliever is perceived compared to the first.
03

Calculate Standard Error of Difference

Calculate the standard error of the difference in proportions using the formula: \[ SE = \sqrt{\frac{\hat{p}_1(1-\hat{p}_1)}{n_1} + \frac{\hat{p}_2(1-\hat{p}_2)}{n_2}} \]Substitute in values: \[ SE = \sqrt{\frac{0.93(1-0.93)}{200} + \frac{0.96(1-0.96)}{450}} \]\[ SE \approx \sqrt{\frac{0.0651}{200} + \frac{0.0384}{450}} \]\[ SE \approx 0.0289 \]
04

Calculate Margin of Error

To calculate the margin of error, use the standard error and a critical value for a 95% confidence level (approximately 1.96 for a normal distribution):\[ ME = 1.96 \times SE \approx 1.96 \times 0.0289 \approx 0.0566 \]
05

Construct Confidence Interval

Create the confidence interval around the estimated proportion difference: \[ (\hat{p}_2 - \hat{p}_1) \pm ME \]This becomes: \[ 0.03 \pm 0.0566 \]The interval is approximately: \[ (-0.0266, 0.0866) \]
06

Analyze Confidence Interval

Since the confidence interval \((-0.0266, 0.0866)\) includes zero, it indicates that there is not enough evidence to conclude that there is a difference in the proportions of all adults who perceived pain relief between the two pain relievers.

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Key Concepts

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

Confidence Interval
A confidence interval provides a range of values that estimate the true value of a population parameter. It offers a way to determine how confident we can be about a particular estimation. The confidence interval is often constructed around estimates like means or proportions in statistics.

In our study, we use a confidence interval to estimate the true difference in proportions of individuals experiencing pain relief between the two pain relievers. The confidence interval is derived by considering the estimated difference and then adjusting this by the margin of error. This interval gives us an idea of how precise our estimate is.

In this scenario, the interval (-0.0266, 0.0866) suggests that the actual difference in the rate of effectiveness between the two pain relievers can range from slightly favoring the first to somewhat more favoring the second. Since the interval includes zero, it implies uncertainty about whether there is a meaningful difference in their performances.
Difference in Proportions
The difference in proportions is a statistical measure that shows the absolute difference between two population proportions. It helps in understanding if one proportion is larger or smaller compared to another.

In our exercise, we calculate the difference in proportions by subtracting the larger reported proportion from the smaller one. For the first pain reliever, the proportion of relief is 0.93, and for the second, it is 0.96. Hence, the difference in proportions is 0.96 - 0.93 = 0.03. This positive difference indicates a small increase in effectiveness of the second pain reliever over the first.

Understanding this concept is vital because it directly helps researchers and statisticians make decisions based on comparative studies, informing them if an intervention is likely more successful than others.
Standard Error
The standard error measures the accuracy with which a sample represents a population. It determines the variability of a sample statistic, like the mean or proportion, by calculating the dispersion from the actual population value.

The standard error of the difference in proportions is calculated in this study to get a sense of the uncertainty associated with our estimated proportion difference. It is a critical step in hypothesis testing and constructing confidence intervals. The formula used is:

\[ SE = \sqrt{\frac{\hat{p}_1(1-\hat{p}_1)}{n_1} + \frac{\hat{p}_2(1-\hat{p}_2)}{n_2}} \]

Substituting the values gives a standard error of approximately 0.0289. This low value indicates a low degree of variation in our estimates, thus increasing our confidence in the results.
Margin of Error
The margin of error is a statistic expressing the amount of random sampling error in a survey's results. It represents the range in which the true proportion of the population will lie with a certain level of confidence.

In our study, the margin of error is calculated to gauge how much our estimate of the difference in proportions could vary due to sample variability. Using a critical value from the normal distribution (commonly 1.96 for a 95% confidence level) allows us to calculate the margin of error:

\[ ME = 1.96 \times SE \approx 0.0566 \]

This margin of error is applied to the calculated difference in proportions to create the confidence interval. Thus, the interval around our estimate provides boundaries within which we expect the true difference to appear, allowing researchers to draw conclusions with quantified uncertainty.

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