Math Problem Statement

Construct a 99% confidence interval for data sets A and B. Data sets A and B are dependent. Assume that the paired data came from a population that is normally distributed. Round to three decimal places.

Solution

To construct a 99% confidence interval for the paired data sets AA and BB, we will follow these steps:

  1. Calculate the differences between corresponding values of AA and BB.
  2. Find the mean of these differences.
  3. Calculate the standard deviation of these differences.
  4. Use the t-distribution to find the critical value for a 99% confidence level.
  5. Construct the confidence interval.

Let's solve it step by step.

Step 1: Calculate the differences

The data sets are:

  • AA: 5.8, 6.8, 8.7, 5.7, 5.8
  • BB: 8.2, 7.1, 7.0, 6.9, 8.3

Calculate the differences D=ABD = A - B: D=5.88.2,6.87.1,8.77.0,5.76.9,5.88.3D = 5.8 - 8.2, \, 6.8 - 7.1, \, 8.7 - 7.0, \, 5.7 - 6.9, \, 5.8 - 8.3 D=2.4,0.3,1.7,1.2,2.5D = -2.4, -0.3, 1.7, -1.2, -2.5

Step 2: Mean of the differences

Dˉ=2.4+(0.3)+1.7+(1.2)+(2.5)5=4.75=0.94\bar{D} = \frac{-2.4 + (-0.3) + 1.7 + (-1.2) + (-2.5)}{5} = \frac{-4.7}{5} = -0.94

Step 3: Standard deviation of the differences

Calculate the standard deviation sDs_D: sD=1n1(DiDˉ)2s_D = \sqrt{\frac{1}{n-1} \sum (D_i - \bar{D})^2} Where n=5n = 5.

Step 4: Critical value for a 99% confidence level

Use the t-distribution with n1=4n-1 = 4 degrees of freedom.

Step 5: Construct the confidence interval

The confidence interval is given by: Dˉ±t(sDn)\bar{D} \pm t^* \left(\frac{s_D}{\sqrt{n}}\right) Where tt^* is the critical value.

Let me calculate these values for you.The calculations yield the following results:

  • Mean of the differences: Dˉ=0.94\bar{D} = -0.94
  • Standard deviation of the differences: sD=1.733s_D = 1.733
  • Critical value for a 99% confidence level: t=4.604t^* = 4.604

The 99% confidence interval for the mean difference is: (4.508,2.628)(-4.508, 2.628)

Therefore, the correct answer is option B: (4.508,2.628)(-4.508, 2.628).

Would you like to delve into any of the details or have more questions?

Related Questions:

  1. What is the formula for calculating the standard deviation of paired differences?
  2. How does the confidence level affect the width of a confidence interval?
  3. Why is the t-distribution used instead of the z-distribution in this case?
  4. How would the confidence interval change if we had a larger sample size?
  5. What are some practical applications of paired sample confidence intervals?

Tip:

When working with small sample sizes (typically n<30n < 30), it's better to use the t-distribution rather than the z-distribution to account for the additional uncertainty in the sample estimate of the standard deviation.

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Math Problem Analysis

Mathematical Concepts

Confidence Intervals
Paired Data Analysis
T-Distribution
Statistical Inference

Formulas

D = A - B (Differences between paired data)
Mean of differences: D̄ = ΣD / n
Standard deviation: s_D = √[Σ(Di - D̄)^2 / (n - 1)]
Confidence Interval: D̄ ± t*(s_D / √n)

Theorems

Central Limit Theorem
Student's T-Distribution

Suitable Grade Level

College Level or Advanced High School (Statistics)