# known.designs

##### Show the 'known' designs

Returns the known study designs for which power and sample size can be calculated within this package.

##### Usage

`known.designs()`

##### Details

This function is for informal purposes and will be used internal for obtaining characteristics of the designs used in calculation formulas.

##### Value

Returns a data.frame with

`no`

= number of the design

`design`

= character string for identifying the design

`df`

= degrees of freedom of the design

`df2`

= 'robust' degrees of freedom of the design

`steps`

= step width in the iterative sample size estimation

`bk`

= so-called design constant in terms of total n

`bkni`

= design constant in terms of number of subjects in (sequence) groups

The design character string has to be used in the functions calls for power and sample size.

##### Note

The design string for higher order crossover designs is named as:
`treatments x sequences x periods`

in case of replicate designs and
`treatments x periods`

in case of crossover designs for more then 2 treatments
with number of sequences equal number of treatments.
The df for the replicate crossover designs are those without carry-over in the model.
Chen, Chow and Liu used models with carry-over, i.e. one df lower than here.
The design constant bk in case of design 2x2x4 is here bk=1.
Chen, Chow and Liu used bk=1.1 due to carry-over in the model.
n is the **total** number of subjects for all designs implemented.
df2 = degrees of freedom for the so-called 'robust' analysis (aka Senn's basic estimator).
These degrees of freedom are often also more appropriate in case of evaluation via a 'true'
mixed model (FDA model for replicate designs).
The design `2x2x2r`

is the 2-treatment-2-sequence-2-period design with
2 repeated targets determined in each period (sequences TT|RR or RR|TT) described
by Liu. Implemented are the characteristics of this design for the evaluation
via assuming no SxF interaction and equal variability for Test and Reference.

##### References

K.-W. Chen, S.-C. Chow and G. Liu "A Note on Sample Size Determination for Bioequivalence Studies with Higher-order Crossover Designs" J. Pharmacokinetics and Biopharmaceutics, Vol. 25, No. 6, p753-765 (1997)

S. Senn "Cross-over Trials in Clinical Research" Second Edition, John Wiley & Sons, Chichester 2002

FDA Guidance for Industry. "Statistical Approaches to Establishing Bioequivalence" U.S. Department of Health and Human Services, Food and Drug Administration, Center for Drug Evaluation and Research (CDER). January 2001

Liu J-P "Use of the Repeated Crossover design in Assessing Bioequivalence" Stat. Med. Vol. 14, 1067-1078 (1995)

##### Examples

```
# NOT RUN {
known.designs()
# }
```

*Documentation reproduced from package PowerTOST, version 1.4-5, License: GPL (>= 2)*