1. What is a Z-Score?

The Z-score (standard score) indicates how many standard deviations an element is from the mean. It's commonly used in Sri Lanka for growth monitoring and statistical analysis.

2. How Does the Calculator Work?

The calculator uses the Z-score formula:

Where:

• \( z \) — Z-score (dimensionless)
• \( x \) — Measured value
• \( \mu \) — Population mean
• \( \sigma \) — Population standard deviation

Explanation: The formula standardizes values to allow comparison across different measurements or populations.

3. Importance of Z-Score Calculation

Details: Z-scores are crucial for growth monitoring in children, identifying outliers in data, and standardizing measurements for comparison.

4. Using the Calculator

Tips: Enter the measured value, population mean, and standard deviation. Standard deviation must be greater than zero.

5. Frequently Asked Questions (FAQ)

Q1: What does a Z-score of 0 mean?
A: A Z-score of 0 indicates the value is exactly at the population mean.

Q2: How are Z-scores used in Sri Lanka?
A: In Sri Lanka, Z-scores are commonly used for university admissions and child growth monitoring.

Q3: What is considered a significant Z-score?
A: Typically, Z-scores beyond ±2 are considered statistically significant, indicating values more than 2 standard deviations from the mean.

Q4: Can Z-scores be negative?
A: Yes, negative Z-scores indicate values below the mean, while positive scores indicate values above the mean.

Q5: How does this differ from T-scores?
A: Z-scores compare to the general population, while T-scores typically compare to a specific reference group (often scaled to mean=50, SD=10).