Description Usage Arguments Details Value References Examples
Generate a design to be used for MaxDiff and related tradeoff exercises.
1 | tradeoff.des(items, shown, vers, tasks, fname=NULL, Rd=20, Rc=NULL, print=TRUE)
|
items |
The total number of items in the tradeoff exercise. |
shown |
The number of items shown in each tradeoff task. |
vers |
The number of blocks or versions in the final design. |
tasks |
The number of tradeoff tasks in each version of the final design. |
fname |
A character string, usually ending in ".txt", indicating the name of the file containing the tradeoff design. |
Rd |
The number of iterations in the design and blocking processes. |
Rc |
The number of iterations in the item by column position optimization routine. |
print |
Boolean indicating whether there is output to the console during execution. |
Replicates the functionality of Sawtooth Software MaxDiff Designer for designing MaxDiff and related tradeoff tasks.
A modified Federov (1972) algorithm is applied to a factor equal in length to the number of items to optimize
the BIB design at vers x tasks
rows and shown
columns.
The optimized design is evaluated for one-way frequencies (equal representation of each item across all
versions and column positions). Designs are also optimized for two-way or pairwise balance across all tasks.
Column position balance is the more computationally-intensive process. The number of iterations required for
this step is determined by the Rc
argument which defaults to the larger of 1,000 or 10 x
the
number of rows in the design. Large design problems may require a larger number of iterations to achieve
optimal column position balance.
Once an optimal design has been found, it is blocked into versions using optBlock
to ensure equal
representation of items within each version. See Wheeler (2004) for a more complete description of the
modified Federov and blocking algorithms used in optimizing these designs.
If fname
is not NULL
a tab-delimited plain-text file is generated in the working
directory containing the levels-coded design.
design |
A matrix consisting of the optimized design and additional variables for card, version and task. |
balance |
Tables of one-way item frequencies, two-way (pairwise) item frequencies, and item frequencies by column position. Means and standard deviations are calculated from all elements of the one-way and column position tables, and from the off-diagonal elements of the two-way (pairwise) table. |
Rc.crit |
The criterion that is minimized to achieve column position balance is output as a vector
( |
time.elapsed |
The time required for the function to execute. |
Federov, V.V. (1972). Theory of optimal experiments. Academic Press, New York.
Wheeler, R.E. (2004). AlgDesign. The R project for statistical computing. (http://www.r-project.org).
1 2 3 4 5 6 7 | ## Example 1:
## typical MaxDiff design with 12 items
des <- tradeoff.des(12, 4, 10, 9)
## Example 2:
## typical paired comparisons design with 14 items
des <- tradeoff.des(14, 2, 6, 14)
|
Loading required package: AlgDesign
tradeoff.des 0.9-2, Mon Mar 30 09:17:53 2020
total iterations: 1000
critical D: 0.01534488, stable: 604 iterations
time elapsed: 1.305092 secs
tradeoff.des 0.9-2, Mon Mar 30 09:17:55 2020
total iterations: 1000
critical D: 0.01046787, stable: 840 iterations
time elapsed: 0.5106826 secs
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