Description Usage Arguments Value Author(s) See Also

This function finds matches for the events without a strata sing the Mahalanobis distrance and nearest neighbor. It is a wrapper for the matchit function from the MatchIt package.

1 | ```
matchmahal(date, casecontrol, matchvars, by, ratio = 1, datewindow, ...)
``` |

`date` |
A vector of dates. |

`casecontrol` |
A vector where 1 indentifies events, 0 identifies potential controls, and NA represent non-event days that are not eligible to be matched (e.g. missing data, or excluded for some other reason). |

`matchvars` |
A matrix where the columns represent variables that will be matched on using the Mahalanobis distrance and nearest neighbor. |

`by` |
A vector of ids or a matrix with columns as the id variables. The events will be found separately within each unique combination of id variables. This is optional. |

`ratio` |
The number of control units to be matched to each case. The default is 1. See documentation for matchit for more details. |

`datewindow` |
A scalar that limits the potential control days to be within a a particular number of days of the range of events. For example, if the events occur on days 100, 101, 150, 151, 152 of the year and datewindow=7 then control days will have day of years in the range of 93 to 159. If missing then all days are eligible. |

data A data.table of matched cases and controls.

nn A summary of the number if cases and controls that were matched. See documentation for matchit for more details.

sum.matched A summary of the quality of each match. See documentation for matchit for more details.

Ander Wilson

MatchIt

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