A researcher would like to evaluate the effectiveness of a pain-relief patch designed for back pain. Prior to testing the patch, each of n = 8 patients rates their current level of back pain on a scale from 1 to 10. After wearing the patch for 90 minutes, a second pain rating is recorded. The data are as follows: Before After 6 2 8 3 9 4 8 1 10 2 5 3 9 8 7 7 a. Compute the mean and variance for the sample of difference scores. b. Do the results indicate that the pain-relief patch has an effect? Use a two-tailed test with α = .05 c. Compute Cohen’s d to measure the size of the effect.
Inverse Normal Distribution
The method used for finding the corresponding z-critical value in a normal distribution using the known probability is said to be an inverse normal distribution. The inverse normal distribution is a continuous probability distribution with a family of two parameters.
Mean, Median, Mode
It is a descriptive summary of a data set. It can be defined by using some of the measures. The central tendencies do not provide information regarding individual data from the dataset. However, they give a summary of the data set. The central tendency or measure of central tendency is a central or typical value for a probability distribution.
Z-Scores
A z-score is a unit of measurement used in statistics to describe the position of a raw score in terms of its distance from the mean, measured with reference to standard deviation from the mean. Z-scores are useful in statistics because they allow comparison between two scores that belong to different normal distributions.
A researcher would like to evaluate the effectiveness of a pain-relief patch designed for back pain. Prior to testing the patch, each of n = 8 patients rates their current level of back pain on a scale from 1 to 10. After wearing the patch for 90 minutes, a second pain rating is recorded. The data are as follows:
Before After
6 2
8 3
9 4
8 1
10 2
5 3
9 8
7 7
a. Compute the mean and variance for the sample of difference scores.
b. Do the results indicate that the pain-relief patch has an effect? Use a two-tailed test with α = .05
c. Compute Cohen’s d to measure the size of the effect.
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