Imagine you are doing a Related-Samples t-test, and you are on Step Three of the hypothesis test. The sample of difference scores that you calculated is -2, -4, -3, +1. What is the correct t-obtained? NOTE: The answer options also show many numbers that you calculate as part of the WORK for getting the t-obtained. VERY IMPORTANT HINT: The SS of these difference scores is 14.00. Group of answer choices
Imagine you are doing a Related-Samples t-test, and you are on Step Three of the hypothesis test. The sample of difference scores that you calculated is -2, -4, -3, +1. What is the correct t-obtained?ÂÂ
NOTE: The answer options also show many numbers that you calculate as part of the WORK for getting the t-obtained.ÂÂ
VERY IMPORTANT HINT: The SS of these difference scores is 14.00.
Group of answer choices
- MD (mean of D’s) = -1.17
SD (standard deviation of D’s) = 2.14
SMD (standard error) = 0.87
t-obt = -1.34
- MD (mean of D’s) = -2.20
SD (standard deviation of D’s) = 3.35
SMD (standard error) = 1.50
t-obt = -1.47
- MD (mean of D’s) = -1.67
SD (standard deviation of D’s) = 3.21
SMD (standard error) = 1.86
t-obt = -0.90
- MD (mean of D’s) = -2.00
SD (standard deviation of D’s) = 2.16
SMD (standard error) = 1.08
t-obt = -1.85
The Correct Answer and Explanation is :
The correct answer is option 4.
Here’s how the calculations work:
- Mean of the Difference Scores (MD):
[
MD = \frac{-2 + (-4) + (-3) + 1}{4} = \frac{-8}{4} = -2.00
]
So, MD is -2.00. - Standard Deviation (SD):
We are given the sum of squares (SS) for the difference scores, which is 14.00. To calculate the SD, we divide the SS by the degrees of freedom (which is (N-1) where (N) is the sample size) and then take the square root:
[
SD = \sqrt{\frac{SS}{N-1}} = \sqrt{\frac{14.00}{4-1}} = \sqrt{\frac{14.00}{3}} = 2.16
] - Standard Error of the Mean Difference (SMD):
The standard error (SMD) is calculated by dividing the SD by the square root of the sample size:
[
SMD = \frac{SD}{\sqrt{N}} = \frac{2.16}{\sqrt{4}} = \frac{2.16}{2} = 1.08
] - t-obtained (t-obt):
Finally, the t-statistic is calculated as:
[
t_{obt} = \frac{MD}{SMD} = \frac{-2.00}{1.08} \approx -1.85
]
Thus, the t-obtained is approximately -1.85, which corresponds to option 4.
Let me generate a visualization of this calculation process for clarity.
Here is the step-by-step visualization of the Related-Samples t-test calculation. It shows how we arrived at the mean of the differences, standard deviation, standard error, and the t-obtained value. Let me know if you need any further explanation!
