\( z = \fracx – \mu\sigma \)Here, \( \mu \) is the population mean and \( \sigma \) the standard deviation. This formula shifts data to center at zero and scales it by standard deviation—making it dimensionless and universally comparable. For example, a customer satisfaction score of 85 with \( \mu = 80 \) and \( \sigma = 5 \) yields \( z = 1 \), placing it one standard deviation above average—regardless of original units. This standardization allows direct comparison of scores across different scales, such as sales velocity in units per day versus regional customer sentiment indices.
| Metric | January | Z-Score | December | Z-Score |
|---|---|---|---|---|
| Customer Satisfaction | 82 | 1.0 | 79 | −0.8 |
| Sales Velocity (units/day) | 45 | −0.5 | 52 | 0.7 |
