# Likelihood Ratio Calculator

Posted by Dinesh onOnline **likelihood ratio** calculator to calculate the value of performing a diagnostic test of patient's expected and target disorder in diagnostic testing.

Likelihood Ratio | Approximate Change in Probability | Effect on Posttest Probability of disease |
---|---|---|

Values between 0 and 1 decrease the probability of disease | ||

0.1 | -45% | Large decrease |

0.2 | -30% | Moderate decrease |

0.5 | -15% | Slight decrease |

1 | 0% | None |

Values greater than 1 increase the probability of disease | ||

1 | 0% | None |

2 | 15% | Slight increase |

5 | 30% | Moderate increase |

10 | 45% | Large increase |

## Calculate Likelihood Ratios in Diagnostic Testing

### Formula:

LR^{+} = (a/(a+c)) / (b/(b+d))

LR^{?} = (c/(a+c)) / (d/(b+d))

T

^{+}= result of the test is positive,

T

^{?}= result of the test is negative,

D

^{+}= present disease,

D

^{?}= absent present,

LR

^{+}= Positive likelihood ratio,

LR

^{?}= Negative likelihood ratio