## No replace, with a sequence?

 Author Message macag006 Expert Group: Forum Members Posts: 4, Visits: 7 I'm trying to randomize by outputs, but with some order still. Is there a command to do so? I've tried several combinations, but with no luck.Specifically, I have a group of trials from "1(a-l)" to "6(a-l)" (72 in total) and another group of trials from "7(a-l)" to "12(a-l)" (another 72 in total). I want to randomly select one stimuli from the first group and then randomly select one trial from the second group, going back and forth between the groups until all stimuli have been used.Any suggestions? Dave Supreme Being Group: Administrators Posts: 9.8K, Visits: 46K That's no problem at all:/ trials = [1,3,5,7,9,11,13,15=noreplace(a1,a2,a3,a4); 2,4,6,8,10,12,14,16=noreplace(b1,b2,b3,b4)]... macag006 Expert Group: Forum Members Posts: 4, Visits: 7 Thank you!For some reason I'm unable to do the following:/ trials = [1-8= noreplace (1a,1b,1c,1d, etc.); 9-16= noreplace (2a,2b,2c,2d, etc.); 17,19,21,23,25= noreplace (3a,3b,3c,3d, etc.); 18,20,22,24,26= noreplace (4a,4b,4c,4d,etc.)]In order for it to work, I must put a square bracket after "9-16= noreplace (2a,2b,2c,2d, etc.)]", however, this then stops the display from running after the 16th trial. If I were to put the trials as "1,3,5,7= noreplace (3a,3b,3d, etc.); 2,4,6,8= noreplace (4a,4b,4c, etc.); 9-16(1a,1b,1c,1d, etc.); 17-26(2a,2b,2c, etc.) it works fine, no square brackets needed until the very end. Why is this? Thanks for your help! Dave Supreme Being Group: Administrators Posts: 9.8K, Visits: 46K Double-check your syntax. There's an error in there somewhere (in the stuff you did not include). Doing/ trials = [1-8= noreplace(1a,1b,1c,1d);     9-16= noreplace (2a,2b,2c,2d);     17,19,21,23,25=noreplace(3a,3b,3c,3d);    18,20,22,24,26= noreplace (4a,4b,4c,4d)]/ validresponse = (57)/ validresponse = (57)/ validresponse = (57)/ validresponse = (57)/ validresponse = (57)/ validresponse = (57)/ validresponse = (57)/ validresponse = (57)/ validresponse = (57)/ validresponse = (57)/ validresponse = (57)/ validresponse = (57)/ validresponse = (57)/ validresponse = (57)/ validresponse = (57)/ validresponse = (57)is perfectly valid and will parse just fine (as you can try for yourself using the above code). macag006 Expert Group: Forum Members Posts: 4, Visits: 7 Thanks Dave! I'll give that a try.