Math Problem Statement

A clinical psychologist claims that as social support increases this causes life satisfaction to increase.

They want to test this experimentally by having 6 students receiving additional social support in their fall semester and then assessing life satisfaction of participants ( = mu1). Then the same 6 students receive no additional social support in their spring semester and are assessed on their life satisfaction during finals ( = mu2) and they want to assess if the difference in stress with no additional finals relative to additional finals with mu1 - mu2.

= mu1 = Additional social support and

= mu2 = No additional social support

They get the following data:

Additional social support No Additional social support 86 70 81 47 82 83 78 69 22 53 96 79 What would be the estimated standard error of the differences (i.e., the denominator of your t-statistic)? Please compute and report to 4 decimal places.

Solution

To compute the estimated standard error of the differences for this paired sample t-test, we need to follow these steps:

Step 1: Find the differences between the paired scores

First, calculate the differences between the scores for each participant when they received additional social support and when they did not.

Difference=μ1μ2\text{Difference} = \mu_1 - \mu_2

Additional Social Support (μ1\mu_1)No Additional Social Support (μ2\mu_2)Difference (DD)
86708670=1686 - 70 = 16
81478147=3481 - 47 = 34
82838283=182 - 83 = -1
78697869=978 - 69 = 9
22532253=3122 - 53 = -31
96799679=1796 - 79 = 17

So the differences are: D=[16,34,1,9,31,17]D = [16, 34, -1, 9, -31, 17].

Step 2: Calculate the mean of the differences (D\overline{D})

D=Dn=16+341+931+176=446=7.3333\overline{D} = \frac{\sum D}{n} = \frac{16 + 34 - 1 + 9 - 31 + 17}{6} = \frac{44}{6} = 7.3333

Step 3: Calculate the variance of the differences

The variance of the differences is given by:

sD2=(DD)2n1s_D^2 = \frac{\sum (D - \overline{D})^2}{n - 1}

Now, subtract the mean from each difference and square the result:

(167.3333)2=75.1111,(347.3333)2=711.1111,(17.3333)2=69.4444(16 - 7.3333)^2 = 75.1111, \quad (34 - 7.3333)^2 = 711.1111, \quad (-1 - 7.3333)^2 = 69.4444 (97.3333)2=2.7778,(317.3333)2=1475.1111,(177.3333)2=93.4444(9 - 7.3333)^2 = 2.7778, \quad (-31 - 7.3333)^2 = 1475.1111, \quad (17 - 7.3333)^2 = 93.4444

Sum these squared differences:

75.1111+711.1111+69.4444+2.7778+1475.1111+93.4444=2426.999975.1111 + 711.1111 + 69.4444 + 2.7778 + 1475.1111 + 93.4444 = 2426.9999

Now divide by n1=61=5n - 1 = 6 - 1 = 5:

sD2=2426.99995=485.39998s_D^2 = \frac{2426.9999}{5} = 485.39998

Step 4: Calculate the standard deviation of the differences

The standard deviation is the square root of the variance:

sD=485.39998=22.0341s_D = \sqrt{485.39998} = 22.0341

Step 5: Compute the estimated standard error of the differences (SEDSE_D)

The standard error of the differences is given by:

SED=sDn=22.03416=22.03412.4495=9.0000SE_D = \frac{s_D}{\sqrt{n}} = \frac{22.0341}{\sqrt{6}} = \frac{22.0341}{2.4495} = 9.0000

Conclusion:

The estimated standard error of the differences is 9.0000 (rounded to four decimal places).

Would you like more details or have any questions?

Here are 5 questions that expand on this information:

  1. How is the t-statistic calculated using the standard error of the differences?
  2. What assumptions are made in a paired sample t-test?
  3. How would you interpret the results if the t-statistic is significant?
  4. How does the standard error change with a larger sample size?
  5. What are some factors that could affect the life satisfaction scores in this experiment?

Tip: Always check that the data meets the assumptions of the paired t-test (normality, independence, etc.) before running the test.

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Math Problem Analysis

Mathematical Concepts

Paired Sample t-test
Descriptive Statistics
Standard Error
Mean Difference

Formulas

Difference = mu1 - mu2
Mean of differences (D̄) = Σ(D) / n
Variance of differences (sD²) = Σ(D - D̄)² / (n - 1)
Standard Deviation (sD) = √sD²
Standard Error (SE) = sD / √n

Theorems

t-distribution
Central Limit Theorem (for estimating error with small sample sizes)

Suitable Grade Level

Undergraduate (Statistics or Psychology courses)