longarm | R Documentation |

This function transforms data from pairwise comparisons to a long arm-based format, i.e., two rows for a pairwise comparison.

```
longarm(
treat1,
treat2,
event1,
n1,
event2,
n2,
mean1,
sd1,
mean2,
sd2,
time1,
time2,
data = NULL,
studlab,
id1 = NULL,
id2 = NULL,
append = TRUE,
keep.duplicated = FALSE,
keep.internal = FALSE
)
```

`treat1` |
Either label for first treatment or a meta-analysis or pairwise object (see Details). |

`treat2` |
Label for second treatment. |

`event1` |
Number of events (first treatment). |

`n1` |
Number of observations (first treatment). |

`event2` |
Number of events (second treatment). |

`n2` |
Number of observations (second treatment) |

`mean1` |
Estimated mean (first treatment). |

`sd1` |
Standard deviation (first treatment). |

`mean2` |
Estimated mean (second treatment). |

`sd2` |
Standard deviation (second treatment). |

`time1` |
Person time at risk (first treatment) |

`time2` |
Person time at risk (second treatment) |

`data` |
An optional data frame containing the study information. |

`studlab` |
A vector with study labels (optional). |

`id1` |
Last character(s) of variable names for additional variables with group specific information for first treatment. |

`id2` |
Last character(s) of variable names for additional variables with group specific information for second treatment. |

`append` |
A logical indicating if data frame provided in argument 'data' should be returned. |

`keep.duplicated` |
A logical indicating if duplicated rows should be returned (see Details). |

`keep.internal` |
A logical indicating if variables generated internally should be returned (typically only relevant for data checking). |

This function transforms data given as one pairwise comparison per row to a long arm-based format with one row per treatment arm. The long arm-based format is, for example, the required input format for WinBUGS.

The function can be used to transform data with a binary,
continuous or count outcome. The corresponding meta-analysis
functions are `metabin`

, `metacont`

and
`metainc`

. Accordingly, a meta-analysis object created
with one of these functions can be provided as argument
`treat1`

. It is also possible to use the longarm function with
an R objected created with `pairwise`

from R
package **netmeta**.

Otherwise, arguments `treat1`

and `treat2`

are mandatory
to identify the individual treatments and, depending on the
outcome, the following additional arguments are mandatory:

event1, n1, event2, n2 (binary outcome);

n1, mean1, sd1, n2, mean2, sd2 (continuous outcome);

time1, n1, time2, n2 (count outcome).

Argument `studlab`

must be provided if several pairwise
comparisons come from a single study with more than two treatments.

The following variables will be returned:

studlab | study label |

treat | treatment label |

n | group sample size (count outcome only if provided) |

events | number of events (binary or count outcome) |

nonevents | number of non-events (binary outcome) |

mean | estimated mean (continuous outcome) |

sd | standard deviation (continuous outcome) |

time | person time at risk (count outcome) |

In addition, the data set provided in argument `data`

will be
returned if argument `append = TRUE`

(default).

Argument `keep.duplicated`

can be used to keep duplicated rows
from the data set. Duplicated rows can occur, for example, in a
three-arm study comparing treatments A and B with placebo. In this
situation, the placebo arm will be returned twice in the data set
in long arm-based format if `keep.duplicated = TRUE`

. By
default, duplicated rows with not be kept in the data set.

A data frame in long arm-based format.

R function `to.long`

from R package
**metafor** is called internally.

Guido Schwarzer guido.schwarzer@uniklinik-freiburg.de

`metabin`

, `metacont`

,
`metainc`

, `pairwise`

```
# Artificial example with three studies
m <- metabin(1:3, 100:102, 4:6, 200:202, studlab = LETTERS[1:3])
# Transform data to long arm-based format
longarm(m)
# Keep internal variables
longarm(m, keep.internal = TRUE)
```

meta documentation built on June 7, 2023, 5:08 p.m.

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