# Mann-Kendall statistic.

### Description

Calculates the Mann-Kendall statistic for monotonic trend. Unlike the function `MannKendall`

, works
for repeat values of time. Used in function `mannkendall`

, which also calculates the p-value by simulation.

### Usage

1 | ```
mannkendall.stat(time, Y)
``` |

### Arguments

`time` |
Vector of values which define the direction of the trend. |

`Y` |
Vector of values for which you want to determine the trend. |

### Details

The statistic is calculated by considering
each case `j`

and considering the subset of observations that have time greater than `time[j]`

. The Mann Kendall
statistic is the number of observations in this subset for which `Y > Y[j]`

minus the number for
which `Y < Y[j]`

.
The statistic is summed over all `j`

. The p-value is calculated by `nreps`

random permutations of the Y values.

### Value

Mann-Kendall statistic

### Author(s)

Jon Barry: Jon.Barry@cefas.co.uk

### References

Mann, H.B. (1945), Nonparametric tests against trend, Econometrica, 13, 245-259. Kendall, M.G. 1975. Rank Correlation Methods, 4th edition, Charles Griffin, London.

### See Also

`mannkendall`

, `power.trend`

, `MannKendall`

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