# Doncaster's measure of dynamic interaction

### Description

The function `Don`

measures the dynamic interaction between two moving objects following
the methods outlined by Doncaster (1990).

### Usage

1 | ```
Don(traj1, traj2, tc = 0, dc = 50)
``` |

### Arguments

`traj1` |
an object of the class |

`traj2` |
same as |

`tc` |
time threshold for determining simultaneous fixes – see function: |

`dc` |
distance tolerance limit (in appropriate units) for defining when two fixes are spatially together. |

### Details

This function can be used to compute the Doncaster (1990) methods for measuring
dynamic interaction between two objects. The Doncaster method tests the proportion
of simultaneous fixes that are below `dc`

against that which would be
expected based on the distribution of distances between all fixes.

### Value

This function first returns a plot, for distance values ranging from 0 to the maximum
distance separating two fixes, of the observed proportion of simultaneous fixes below
each distance value. The expected values based on all fixes are also included.
Second, a list is returned that contains the contingency table of simultaneous fixes
(paired) and non-paired fixes below and above `dc`

, along with the
associated *p*-value from the Chi-squared test.

conTable – contingency table showing frequency of paired and non-paired fixes above and below

`dc`

.p.value –

*p*-value from the Chi-squared test of`conTable`

.

### References

Doncaster, C.P. (1992) Non-parametric estimates of interaction from radio-tracking
data. *Journal of Theoretical Biology*, **143**: 431-443.

### See Also

GetSimultaneous

### Examples

1 2 3 4 5 |

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