Math Problem Statement
You wish to test the following claim () at a significance level of . For the context of this problem, where the first data set represents a pre-test and the second data set represents a post-test. (Each row represents the pre and post test scores for an individual. Be careful when you enter your data and specify what your and are so that the differences are computed correctly.)
You believe the population of difference scores is normally distributed, but you do not know the standard deviation. You obtain the following sample of data: pre-test post-test 58.3 -20.6 46.1 -61.4 75.7 64.9 49 11.4 59.7 90.5 64.4 88.9 61.3 -31.2 50.2 2.7 52.9 110.5 79.2 93.8 52.9 -8.7 52.2 76.7 65.8 -26.7 39.8 5.1 66.6 57.1 69 74.5 64 43.1 70.4 115.9
What is the test statistic for this sample? test statistic = (Report answer accurate to 4 decimal places.)
What is the p-value for this sample? p-value = (Report answer accurate to 4 decimal places.)
Solution
To determine the test statistic and p-value for this paired sample, we need to carry out a hypothesis test based on the paired differences between the pre-test and post-test scores for each individual. Here is the detailed process:
Step 1: Calculate the Differences
Define , where represents the pre-test scores and the post-test scores. Compute the differences for each pair.
Step 2: Calculate the Sample Mean and Sample Standard Deviation of the Differences
Once we have the differences , calculate:
- The mean of the differences, .
- The standard deviation of the differences, .
Step 3: Set Up the Hypotheses
Given the context, let's assume we are testing whether there is a significant difference between the pre-test and post-test scores. This is a two-tailed test.
The hypotheses can be defined as:
- Null hypothesis:
- Alternative hypothesis:
Step 4: Calculate the Test Statistic
The test statistic for the paired -test is given by: where is the number of pairs.
Step 5: Find the -value
Using the -distribution with degrees of freedom, find the two-tailed -value for the computed -statistic.
I'll carry out these calculations to get the precise values.The test statistic for this sample is approximately:
The -value for this sample is approximately:
If you have further questions about these calculations or need additional details, please let me know.
Additional Questions for Practice
- What would change if the test were one-tailed instead of two-tailed?
- How do we interpret the p-value in terms of the significance level?
- If the pre-test and post-test were from different individuals (independent samples), how would the test change?
- How would the conclusion differ if the p-value was less than the significance level?
- What is the importance of checking that the differences are normally distributed?
Tip:
When conducting a paired t-test, always check if your data meet the assumption of normality for the differences, especially with small sample sizes.
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Math Problem Analysis
Mathematical Concepts
Paired sample t-test
Hypothesis testing
Statistical significance
Formulas
Test statistic for paired t-test: t = (D̄) / (sD / sqrt(n))
Mean of differences: D̄
Standard deviation of differences: sD
Theorems
Central Limit Theorem
Student's t-distribution
Suitable Grade Level
College or advanced high school statistics
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