# Calculates a rank-based confidence interval

### Description

np.nv gives a two-sided rank-based confidence interval with normal approximation for the difference of two dependent proportions. Data are assumed to be of a fourfold table, which contains the numbers of concordance and the numbers of discordance of two dependent methods.

### Usage

1 |

### Arguments

`a` |
first number of concordant paires as described above |

`b` |
first number of discordant paires as described above |

`c` |
second number of discordant paires as described above |

`d` |
second number of concordant paires as described above |

`n` |
number of observed objects |

`alpha` |
type I error; between zero and one |

### Details

The normal approximation is used for the critical value for the interval.

### Value

A list with class '"htest"' containing the following components:

`conf.int ` |
a confidence interval for the difference in proportions |

`estimate ` |
estimated difference in proportions |

### Author(s)

Daniela Wenzel, Antonia Zapf

### References

Lange, K. and Brunner, E. (2012). Sensitivity, Specificity and ROC-curves in multiple reader diagnostic trials-A unified, nonparametric approach. Statistical Methodology 9, 490-500.

### Examples

1 2 | ```
# a=10, b=15, c=5, d=20, n=50, type I error is 0.05
conf.int=np.nv(10,15,5,20,50,0.05)
``` |