Searching for and Analyzing Designs with Two-Level Factors - Search Strategy Tab

Select the Search strategy tab of the Searching for and Analyzing Designs with Two-Level Factors dialog to access the options described here.

Search strategy

There are two search strategies available in the Search strategy group box: Comprehensive search of all generators and Quick search (tree search of generators).

Comprehensive search of all generators

Select the Comprehensive search of all generators option button to specify a comprehensive search, covering all possible non-isomorphic sets of generators. Isomorphic sets of generators are sets that are the same except for relabeling of the factors. For example, the generator set 6=123 and 7=234 is isomorphic with the generator set 6=134 and 7=345, because 1, 2, 3, and 4, in the first set are merely replaced with 1, 3, 4, and 5, respectively, in the second set. Selecting the Comprehensive search of all generators option button, it should be emphasized, can result in very long searches requiring considerable memory when the desired design includes a large number of factors, because the sets of non-isomorphic generators that are searched can become very large. Alternatively, the Quick search option (see below) conducts a non-comprehensive search, but will often much more quickly find a design meeting the specified criteria.

Quick search (tree search of generators)

Select the Quick search (tree search of generators) option button to specify a noncomprehensive design search. Although the quick search option sometimes fails to find the desired design when such a design does exist, it often finds a design meeting the specified criteria much more quickly than using the Comprehensive search of all generators option (see above).

Search direction

Use the options in the Search direction group box to search either From lowest to highest order interaction or From highest to lowest order interaction.

From lowest to highest order interaction

Select the From lowest to highest order interaction option button to produce a search for the desired design that begins with sets of generators containing the lowest-order interactions and ends with sets containing the highest-order interactions, choosing the first set of generators that produces the "best" design.

From highest to lowest order interaction

Select the From highest to lowest order interaction option button to produce a search for the desired design that begins with sets of generators containing the highest-order interactions and ends with sets containing the lowest-order interactions, choosing the first set of generators that produces the "best" design.

Max search time (in seconds)

STATISTICA uses a default two minute (120 second) limit for searching for a design. If the search is not completed within that time, the best design found up to that point is reported. A longer search time limit can be specified by entering the desired search time limit in the Maximum search time box. See also the discussion on search times in 2(k-p) Maximally Unconfounded and Minimum Aberration Designs.

Click the OK button on the Searching for and Analyzing Designs with Two-Level Factors dialog to start the search and display the Searching for Designs dialog, which displays information allowing you to monitor the search. The number of designs that have been processed and the elapsed time of the search in seconds are displayed as the search progresses. The status of the search, i.e., whether or not a design has been found, is also displayed. If a valid design has been found, you can click the OK button to terminate the search and review the current design. If a valid design has not been found and the search is taking longer than you would like, you can click the Cancel button to terminate the search and return to the Searching for and Analyzing Designs with Two-Level Factors dialog to respecify the search.

For more detailed information on search criteria and search options, see 2(k-p) Maximally Unconfounded and Minimum Aberration Designs.