## BalanceTrials

##### >Psychtoolbox>PsychProbability

BalanceTrials balances a set of factors given the factor levels. It is

identical to BalanceFactors except that the first argument is the number

of trials desired. It outputs one or more vectors containing factor

values for each trial, balanced and, optionally, randomized.

[F1, F2, …] = BalanceTrials(NTRIALS, RND, LVL1, LVL2, …)

BalanceTrials must be called with three or more input arguments. The

first argument, NTRIALS, specifies the number of trials desired. The

second argument, RAND, determines whether or not the returned factors

should be shuffled (non-zero values lead to shuffling).

The remaining input arguments specify the levels for each of a set of

factors. Factor levels can be specified as numeric vectors or cell

arrays (e.g., for category names). The returned factor lists will be the

same class as the corresponding levels.

WARNING: If NTRIALS is not a multiple of the product of the number of

levels, then the actual number of trials generated will be more than

NTRIALS. To detect this situation, test whether numel(F1) == NTRIALS.

### EXAMPLES:

[targetPresent, setSize] = BalanceTrials(80, 0, 0:1, [3 6 9 12]);

[target, setSize, dur] = …

BalanceTrials(72, 1, [0 1], [4 8 12], [0 100 200]);

[samediff, mask] = …

BalanceTrials(20, 1, {‘same’, ‘diff’}, {‘pattern’, ‘meta’});

See also: BalanceFactors

`Psychtoolbox/PsychProbability/BalanceTrials.m`