Factorial design means that all possible combinations of the variable values are taken. When the experment is run, expcontrol generates a stimulus list consisting of a user specified number of blocks. The trials within each block can be randomized. Optionally, a fixed seed can be supplied to the random number generator. This is useful when a particular experiment is to be reproduced exactly.
Randomization is done individually within each block.
The resulting stimulus list can be viewed from the setup dialog. Each experiment has an associated logfile , and one or more datafile s. The experimenter must provide a logfile name, preferably in an empty directory, before the experiment is run for the first time. Each time the experiment is run, expcontrol will write an entry to the logfile, and create a new datafile in which it will store the results of the experminet. The first format has a header giving the names of all data items, followed by a blank line, followed by all data in tab-delimited form in one line per trial.