# find.BIB: Generation of Balanced Incomplete Block Designs Using the... In crossdes: Construction of Crossover Designs

## Description

The function `optBlock` of the library `AlgDesign` is used to search for balanced incomplete block designs (BIBDs). The design is assigned to a matrix where rows represent blocks (subjects) and columns represent periods.

## Usage

 `1` ```find.BIB(trt, b, k, iter = 30) ```

## Arguments

 `trt` An integer > 1 giving the number of treatments of the design. `b` An integer > 1 giving the number of rows (subjects) of the design. `k` An integer > 1 giving the number of columns (periods) of the design. `iter` The number of iterations of the function `optBlock`

## Details

The function `optBlock` tries to find a D-optimal block design for the specified parameters. The resulting design need not be a BIBD. The necessary conditions for the existence are that bk/trt and bk(k-1)/(trt(trt-1)) positive integers. They are NOT checked automatically. Even if they are fulfilled, there need not be a BIBD. If no BIBD is found, the function is iterated. If no BIBD is found after `iter` iterations, the search is terminated. The resulting design should be checked by the user applying `isGYD`.

## Value

A matrix that represents the experimental design.

## Note

As indicated above, the returned design is not necessarily a BIBD design.

Oliver Sailer

## References

Wheeler, R.E. (2004). optBlock. AlgDesign. The R project for statistical computing http://www.r-project.org/

`get.plan`, `optBlock`

## Examples

 ```1 2 3 4``` ```find.BIB(10,30,4) # BIBD find.BIB(3,3,3) # BIBD find.BIB(5,5,3, 100) # There is no BIBD for these parameters # isGYD(find.BIB(5,5,3, 100)) ```

### Example output

```Loading required package: AlgDesign
[,1] [,2] [,3] [,4]
[1,]    5    6    7   10
[2,]    2    3    4    6
[3,]    2    5    7    9
[4,]    2    3    5    7
[5,]    4    7    8   10
[6,]    5    6    8   10
[7,]    1    2    5    8
[8,]    1    4    7   10
[9,]    1    2    4    6
[10,]    2    4    8    9
[11,]    4    5    6    9
[12,]    3    7    8    9
[13,]    3    4    6    9
[14,]    3    4    5    7
[15,]    1    3    6    8
[16,]    1    2    6    7
[17,]    3    4    8   10
[18,]    1    3    9   10
[19,]    1    4    5    9
[20,]    2    4    7    8
[21,]    2    3    5   10
[22,]    6    7    9   10
[23,]    1    3    5    8
[24,]    2    8    9   10
[25,]    1    3    7    9
[26,]    1    6    7    8
[27,]    1    4    5   10
[28,]    1    2    9   10
[29,]    2    3    6   10
[30,]    5    6    8    9
[,1] [,2] [,3]
[1,]    1    2    3
[2,]    1    2    3
[3,]    1    2    3
[,1] [,2] [,3]
[1,]    2    3    5
[2,]    1    3    4
[3,]    2    4    5
[4,]    1    2    4
[5,]    1    3    5
```

crossdes documentation built on May 30, 2017, 4:14 a.m.