magine that a professor of sociology has two teaching assistants (TAs) who will help him grade assignments for the duration of the semester. The professor wants to make sure that he and the TAs are well calibrated with one another, so he has all three of them grade the first assignment independently. Because the professor grades every assignment on a curve, he first converts the students’ scores to z-scores for each grader. The following table shows the z-scores for a population of 10 students in his class for each grader. Professor Teaching Assistant #1 Teaching Assistant #2 Student 1 1.43 1.05 0.39 Student 2 -0.57 -1.33 0.87 Student 3 0.35 0.27 -0.94 Student 4 0.72 0.90 2.24 Student 5 -1.41 -1.23 -0.50 Student 6 0.10 0.27 0.56 Student 7 -2.04 -1.71 -0.94 Student 8 0.76 1.19 0.03 Student 9 0.47 0.56 -0.50 Student 10 0.18 0.03 -1.21 The professor is going to use the z-scores to calculate the correlation coefficient between his scores and those of his TAs. To calculate the correlation coefficient, he sums the products of the z-scores. The professor should divide this sum by .
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.
|
Professor
|
Teaching Assistant #1
|
Teaching Assistant #2
|
---|---|---|---|
Student 1 | 1.43 | 1.05 | 0.39 |
Student 2 | -0.57 | -1.33 | 0.87 |
Student 3 | 0.35 | 0.27 | -0.94 |
Student 4 | 0.72 | 0.90 | 2.24 |
Student 5 | -1.41 | -1.23 | -0.50 |
Student 6 | 0.10 | 0.27 | 0.56 |
Student 7 | -2.04 | -1.71 | -0.94 |
Student 8 | 0.76 | 1.19 | 0.03 |
Student 9 | 0.47 | 0.56 | -0.50 |
Student 10 | 0.18 | 0.03 | -1.21 |
|
Professor
|
Teaching Assistant #1
|
---|---|---|
Teaching Assistant #1 | 1 | |
Teaching Assistant #2 | 0.36 | 0.31 |
Trending now
This is a popular solution!
Step by step
Solved in 2 steps