A customer service department asks its customers to rate their over-the-phone service on a scale of 1-20 immediately after their service has been completed. The department then matches each customer's rating with the number of minutes the person waited on hold. The accompanying table shows the ratings and number of minutes on hold for 10 randomly selected customers. Minutes Rating 5 14 8 12 0 17 4 10 6 13 2 15 9 15 2 20 8 14 5 13
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 customer service department asks its customers to rate their over-the-phone service on a scale of 1-20 immediately after their service has been completed. The department then matches each customer's rating with the number of minutes the person waited on hold. The accompanying table shows the ratings and number of minutes on hold for 10 randomly selected customers.
|
Minutes
|
Rating
|
|
|---|---|---|
|
5
|
14
|
|
|
8
|
12
|
|
|
0
|
17
|
|
|
4
|
10
|
|
|
6
|
13
|
|
|
2
|
15
|
|
|
9
|
15
|
|
|
2
|
20
|
|
|
8
|
14
|
|
|
5
|
13
|
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