The NORMSINV function in Excel is a powerful tool used to find the inverse of the standard normal cumulative distribution function. This function is essential in statistics for determining critical values, enabling users to assess probabilities associated with normally distributed data.

Syntax

NORMSINV(probability)

• probability: A decimal value representing the probability for which you want to find the corresponding z-score. This value must be between 0 and 1.

Example #1

=NORMSINV(0.95)

In this example, the function calculates the z-score for the 95th percentile of the standard normal distribution. The result is approximately 1.645.

Example #2

=NORMSINV(0.5)

This function call computes the z-score for the 50th percentile. The result is 0, indicating that this score is the median of the distribution.

Example #3

=NORMSINV(0.025)

Here, the function finds the z-score for the 2.5th percentile, resulting in approximately -1.96, which is useful for establishing confidence intervals in statistical analysis.

Error handling

• NUM!: Indicates that the input value is not between 0 and 1. Ensure your probability is a valid decimal within this range.
• VALUE!: Suggests that the argument is of the wrong type. Make sure to input a numerical value for probability.

Conclusion

The NORMSINV function is a valuable resource for anyone working with normal distributions in Excel. By understanding its parameters and potential errors, users can effectively apply this function in various statistical analyses, facilitating a deeper insight into their data.