One year Sam had the lowest ERA (earned-run average, mean number of runs yielded per nine innings pitched) of any male pitcher at his school, with an ERA of 3.05. Also, Nina had the lowest ERA of any female pitcher at the school with an ERA of 3.34. For the males, the mean ERA was 4.705 and the standard deviation was 0.852. For the females, the mean ERA was 4.554 and the standard deviation was 0.501. Find their respective Z-scores. Which player had the better year relative to their peers, Sam or Nina? (Note: In general, the lower the ERA, the better the pitcher.) Sam had an ERA with a z-score of Nina had an ERA with a z-score of (Round to two decimal places as needed.)
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.
![**Calculating Z-Scores for ERA in Baseball**
In one particular year, Sam achieved the lowest ERA (earned-run average, the mean number of runs yielded per nine innings pitched) among male pitchers at his school, with an ERA of 3.05. Nina, similarly, had the lowest ERA among female pitchers at her school, with an ERA of 3.34.
### Statistical Comparison:
- **Males:**
- Mean ERA: 4.705
- Standard Deviation: 0.852
- **Females:**
- Mean ERA: 4.554
- Standard Deviation: 0.501
### Task: Calculate and Compare Z-Scores
Calculate the Z-scores for both Sam and Nina to determine who performed better relative to their peers. The formula for calculating a Z-score is:
\[ Z = \frac{(X - \text{Mean})}{\text{Standard Deviation}} \]
**Sam's Z-score**
\[ Z = \frac{(3.05 - 4.705)}{0.852} \]
**Nina's Z-score**
\[ Z = \frac{(3.34 - 4.554)}{0.501} \]
### Determine the Better Performance:
A lower ERA generally indicates better performance for a pitcher, and a lower Z-score represents a performance further below the mean of the group.
**Note:** For accuracy, round your calculations to two decimal places.
**Exercise:**
Fill in the blanks with the calculated Z-scores:
- Sam had an ERA with a Z-score of ______
- Nina had an ERA with a Z-score of ______
Evaluate who had the better relative performance based on their Z-scores.](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Fb0c7ed93-16ac-4709-a60a-fa510093f846%2F4596e6fc-ad60-45cc-819e-58d5af5ff266%2Fbuzari8.jpeg&w=3840&q=75)
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