Daily DAX : Day 398 CHISO.INV

Power BI DAX: CHISQ.INV Function

The CHISQ.INV function in DAX returns the inverse of the left-tailed probability of the chi-squared (χ²) distribution. It is used in statistical analysis to find the critical value from the chi-squared distribution for a given probability and degrees of freedom.

Syntax

CHISQ.INV(probability, deg_freedom)

Parameters

  • probability – A decimal number between 0 and 1 (exclusive) representing the probability associated with the chi-squared distribution.
  • deg_freedom – An integer representing the degrees of freedom. Must be ≥ 1.

Return Value

Returns a numeric value — the critical chi-squared value (χ²) such that the area to the left of this value under the chi-squared distribution curve equals the specified probability.

Example:

Critical Value = CHISQ.INV(0.95, 10)

Returns approximately 18.307 — meaning 95% of the chi-squared distribution with 10 degrees of freedom lies to the left of 18.307.

Use Cases

  • Goodness-of-Fit Testing: Determine the critical χ² value to compare against a test statistic in a Chi-Square Goodness-of-Fit test.
  • Contingency Table Analysis: Set significance thresholds for independence tests in cross-tabulated data.
  • Confidence Interval Construction: Estimate thresholds for variance in normally distributed data.
  • Risk & Quality Control: Establish control limits in statistical process control using χ²-based variance monitoring.

Practical DAX Measure Example

Chi-Square Critical (95%, df=5) = 
CHISQ.INV(0.95, 5)

Result: ~11.0705

Use in a card visual or conditional logic to flag when observed χ² exceeds this threshold.

Notes

  • CHISQ.INV is the left-tailed inverse. For right-tailed (common in hypothesis testing), use 1 - probability with CHISQ.INV.RT.
  • Returns BLANK if inputs are invalid (e.g., probability ≤ 0 or ≥ 1, non-integer or negative degrees of freedom).
  • Available in Power BI, Excel (as CHISQ.INV), and SQL Server Analysis Services.

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