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random trial selection

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plush	plush posted 7 Years Ago Topic Details Share Topic
Group: Forum Members Posts: 57, Visits: 96	Hi guys, I wish to randomly start a trial. I was thinking of branching: <trial agencyneg> /branch = [trial.agencynegA] /branch = [trial.agencynegL] </trial> <trial agencypos> /branch = [trial.agencyposA] /branch = [trial.agencyposL] </trial> <block main> / trials = [1-10 = noreplace (agencypos, agencyneg); 11-12 = noreplace (eva_pos, eva_neg)] </block> However this always starts the first trial of the branch procedure. Any advice is appreciated. Thx!
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Dave	Dave posted 7 Years Ago ANSWER Post Details Share Post
Group: Administrators Posts: 12K, Visits: 98K	+x plush - Tuesday, January 17, 2017 Hi guys, I wish to randomly start a trial. I was thinking of branching: <trial agencyneg> /branch = [trial.agencynegA] /branch = [trial.agencynegL] </trial> <trial agencypos> /branch = [trial.agencyposA] /branch = [trial.agencyposL] </trial> <block main> / trials = [1-10 = noreplace (agencypos, agencyneg); 11-12 = noreplace (eva_pos, eva_neg)] </block> However this always starts the first trial of the branch procedure. Any advice is appreciated. Thx! /branch attributes are checked in the order they are given. The first /branch that applies is executed. Since both of your /branches are unconditional, that will necessarily always be the first one. The solution is to use <list> elements. I.e. <trial agencyneg> / branch = [ list.agencynegtrials.nextvalue ] / trialduration = 0 </trial> <trial agencypos> / branch = [ list.agencypostrials.nextvalue ] / trialduration = 0 </trial> <list agencynegtrials> / items = (trial.agencynegA, trial.agencynegL) </list> <list agencypostrials> / items = (trial.agencyposA, trial.agencyposL) </list> <block main> / trials = [1-10 = noreplace(agencypos, agencyneg); 11-12 = noreplace(eva_pos, eva_neg)] </block>
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