Categorical and Diagnostic Rates

Number Needed to Harm Calculator

Calculates the number needed to harm from an absolute risk increase. The worked condition keeps the inputs and convention visible for checking.

Diagnostic inputs

Set the labeled inputs

Calculated result

Number Needed to Harm

Result

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1/absolute risk increase

How to carry the result forward before comparing methods for number needed to harm

Calculates the number needed to harm from an absolute risk increase. The named quantity is number needed to harm calculator. This is section 1 of the number needed to harm discussion.

Save the inputs, formula convention, units, exclusions, and unrounded output with this result. This statement is conditional on the number needed to harm setup and section 1.

For number needed to harm, preserve the source definition, the stated units, and the named convention beside the displayed number. A second analyst should be able to reconstruct the same result without guessing which population or setup was intended.

The quantity this page defines when the result is reused for number needed to harm

The harm outcome and time horizon determine how this number should be interpreted. The named quantity is number needed to harm calculator. This is section 2 of the number needed to harm discussion.

Increasing risk from .10 to .15 gives NNH 20. This statement is conditional on the number needed to harm setup and section 2.

For number needed to harm, preserve the denominator choice, the stated units, and the named convention beside the displayed number. A second analyst should be able to reconstruct the same result without guessing which population or setup was intended.

A direct numerical check in the worked condition for number needed to harm

The harm outcome and time horizon determine how this number should be interpreted. The named quantity is number needed to harm calculator. This is section 3 of the number needed to harm discussion.

Save the inputs, formula convention, units, exclusions, and unrounded output with this result. This statement is conditional on the number needed to harm setup and section 3.

For number needed to harm, preserve the comparison group, the stated units, and the named convention beside the displayed number. A second analyst should be able to reconstruct the same result without guessing which population or setup was intended.

Interpreting the result before reporting for number needed to harm

Calculates the number needed to harm from an absolute risk increase. The named quantity is number needed to harm calculator. This is section 4 of the number needed to harm discussion.

Increasing risk from .10 to .15 gives NNH 20. This statement is conditional on the number needed to harm setup and section 4.

For number needed to harm, preserve the time boundary, the stated units, and the named convention beside the displayed number. A second analyst should be able to reconstruct the same result without guessing which population or setup was intended.

Keeping a reproducible record under the stated model for number needed to harm

The harm outcome and time horizon determine how this number should be interpreted. The named quantity is number needed to harm calculator. This is section 5 of the number needed to harm discussion.

Save the inputs, formula convention, units, exclusions, and unrounded output with this result. This statement is conditional on the number needed to harm setup and section 5.

For number needed to harm, preserve the design boundary, the stated units, and the named convention beside the displayed number. A second analyst should be able to reconstruct the same result without guessing which population or setup was intended.

The design boundary when the sample changes for number needed to harm

The harm outcome and time horizon determine how this number should be interpreted. The named quantity is number needed to harm calculator. This is section 6 of the number needed to harm discussion.

Increasing risk from .10 to .15 gives NNH 20. This statement is conditional on the number needed to harm setup and section 6.

For number needed to harm, preserve the rounding rule, the stated units, and the named convention beside the displayed number. A second analyst should be able to reconstruct the same result without guessing which population or setup was intended.

The scale of the output during an independent review for number needed to harm

Calculates the number needed to harm from an absolute risk increase. The named quantity is number needed to harm calculator. This is section 7 of the number needed to harm discussion.

Save the inputs, formula convention, units, exclusions, and unrounded output with this result. This statement is conditional on the number needed to harm setup and section 7.

For number needed to harm, preserve the reference population, the stated units, and the named convention beside the displayed number. A second analyst should be able to reconstruct the same result without guessing which population or setup was intended.

A related calculation is cohen kappa agreement.

The reference quantity at the chosen parameters for number needed to harm

The harm outcome and time horizon determine how this number should be interpreted. The named quantity is number needed to harm calculator. This is section 8 of the number needed to harm discussion.

Increasing risk from .10 to .15 gives NNH 20. This statement is conditional on the number needed to harm setup and section 8.

For number needed to harm, preserve the interpretation limit, the stated units, and the named convention beside the displayed number. A second analyst should be able to reconstruct the same result without guessing which population or setup was intended.